Antoine Pitrou | e1bc898 | 2011-01-02 22:12:22 +0000 | [diff] [blame] | 1 | :mod:`ssl` --- TLS/SSL wrapper for socket objects |
| 2 | ================================================= |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 3 | |
| 4 | .. module:: ssl |
Antoine Pitrou | e1bc898 | 2011-01-02 22:12:22 +0000 | [diff] [blame] | 5 | :synopsis: TLS/SSL wrapper for socket objects |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 6 | |
| 7 | .. moduleauthor:: Bill Janssen <bill.janssen@gmail.com> |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 8 | .. sectionauthor:: Bill Janssen <bill.janssen@gmail.com> |
| 9 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 10 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 11 | .. index:: single: OpenSSL; (use in module ssl) |
| 12 | |
| 13 | .. index:: TLS, SSL, Transport Layer Security, Secure Sockets Layer |
| 14 | |
Raymond Hettinger | 469271d | 2011-01-27 20:38:46 +0000 | [diff] [blame] | 15 | **Source code:** :source:`Lib/ssl.py` |
| 16 | |
| 17 | -------------- |
| 18 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 19 | This module provides access to Transport Layer Security (often known as "Secure |
| 20 | Sockets Layer") encryption and peer authentication facilities for network |
| 21 | sockets, both client-side and server-side. This module uses the OpenSSL |
| 22 | library. It is available on all modern Unix systems, Windows, Mac OS X, and |
| 23 | probably additional platforms, as long as OpenSSL is installed on that platform. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 24 | |
| 25 | .. note:: |
| 26 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 27 | Some behavior may be platform dependent, since calls are made to the |
| 28 | operating system socket APIs. The installed version of OpenSSL may also |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 29 | cause variations in behavior. For example, TLSv1.1 and TLSv1.2 come with |
| 30 | openssl version 1.0.1. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 31 | |
Christian Heimes | 3046fe4 | 2013-10-29 21:08:56 +0100 | [diff] [blame] | 32 | .. warning:: |
Antoine Pitrou | 9eefe91 | 2013-11-17 15:35:33 +0100 | [diff] [blame] | 33 | Don't use this module without reading the :ref:`ssl-security`. Doing so |
| 34 | may lead to a false sense of security, as the default settings of the |
| 35 | ssl module are not necessarily appropriate for your application. |
Christian Heimes | 3046fe4 | 2013-10-29 21:08:56 +0100 | [diff] [blame] | 36 | |
Christian Heimes | 3046fe4 | 2013-10-29 21:08:56 +0100 | [diff] [blame] | 37 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 38 | This section documents the objects and functions in the ``ssl`` module; for more |
| 39 | general information about TLS, SSL, and certificates, the reader is referred to |
| 40 | the documents in the "See Also" section at the bottom. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 41 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 42 | This module provides a class, :class:`ssl.SSLSocket`, which is derived from the |
| 43 | :class:`socket.socket` type, and provides a socket-like wrapper that also |
| 44 | encrypts and decrypts the data going over the socket with SSL. It supports |
Antoine Pitrou | dab6426 | 2010-09-19 13:31:06 +0000 | [diff] [blame] | 45 | additional methods such as :meth:`getpeercert`, which retrieves the |
| 46 | certificate of the other side of the connection, and :meth:`cipher`,which |
| 47 | retrieves the cipher being used for the secure connection. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 48 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 49 | For more sophisticated applications, the :class:`ssl.SSLContext` class |
| 50 | helps manage settings and certificates, which can then be inherited |
| 51 | by SSL sockets created through the :meth:`SSLContext.wrap_socket` method. |
| 52 | |
| 53 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 54 | Functions, Constants, and Exceptions |
| 55 | ------------------------------------ |
| 56 | |
| 57 | .. exception:: SSLError |
| 58 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 59 | Raised to signal an error from the underlying SSL implementation |
| 60 | (currently provided by the OpenSSL library). This signifies some |
| 61 | problem in the higher-level encryption and authentication layer that's |
| 62 | superimposed on the underlying network connection. This error |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 63 | is a subtype of :exc:`OSError`. The error code and message of |
| 64 | :exc:`SSLError` instances are provided by the OpenSSL library. |
| 65 | |
| 66 | .. versionchanged:: 3.3 |
| 67 | :exc:`SSLError` used to be a subtype of :exc:`socket.error`. |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 68 | |
Antoine Pitrou | 3b36fb1 | 2012-06-22 21:11:52 +0200 | [diff] [blame] | 69 | .. attribute:: library |
| 70 | |
| 71 | A string mnemonic designating the OpenSSL submodule in which the error |
| 72 | occurred, such as ``SSL``, ``PEM`` or ``X509``. The range of possible |
| 73 | values depends on the OpenSSL version. |
| 74 | |
| 75 | .. versionadded:: 3.3 |
| 76 | |
| 77 | .. attribute:: reason |
| 78 | |
| 79 | A string mnemonic designating the reason this error occurred, for |
| 80 | example ``CERTIFICATE_VERIFY_FAILED``. The range of possible |
| 81 | values depends on the OpenSSL version. |
| 82 | |
| 83 | .. versionadded:: 3.3 |
| 84 | |
Antoine Pitrou | 41032a6 | 2011-10-27 23:56:55 +0200 | [diff] [blame] | 85 | .. exception:: SSLZeroReturnError |
| 86 | |
| 87 | A subclass of :exc:`SSLError` raised when trying to read or write and |
| 88 | the SSL connection has been closed cleanly. Note that this doesn't |
| 89 | mean that the underlying transport (read TCP) has been closed. |
| 90 | |
| 91 | .. versionadded:: 3.3 |
| 92 | |
| 93 | .. exception:: SSLWantReadError |
| 94 | |
| 95 | A subclass of :exc:`SSLError` raised by a :ref:`non-blocking SSL socket |
| 96 | <ssl-nonblocking>` when trying to read or write data, but more data needs |
| 97 | to be received on the underlying TCP transport before the request can be |
| 98 | fulfilled. |
| 99 | |
| 100 | .. versionadded:: 3.3 |
| 101 | |
| 102 | .. exception:: SSLWantWriteError |
| 103 | |
| 104 | A subclass of :exc:`SSLError` raised by a :ref:`non-blocking SSL socket |
| 105 | <ssl-nonblocking>` when trying to read or write data, but more data needs |
| 106 | to be sent on the underlying TCP transport before the request can be |
| 107 | fulfilled. |
| 108 | |
| 109 | .. versionadded:: 3.3 |
| 110 | |
| 111 | .. exception:: SSLSyscallError |
| 112 | |
| 113 | A subclass of :exc:`SSLError` raised when a system error was encountered |
| 114 | while trying to fulfill an operation on a SSL socket. Unfortunately, |
| 115 | there is no easy way to inspect the original errno number. |
| 116 | |
| 117 | .. versionadded:: 3.3 |
| 118 | |
| 119 | .. exception:: SSLEOFError |
| 120 | |
| 121 | A subclass of :exc:`SSLError` raised when the SSL connection has been |
Antoine Pitrou | f3dc2d7 | 2011-10-28 00:01:03 +0200 | [diff] [blame] | 122 | terminated abruptly. Generally, you shouldn't try to reuse the underlying |
Antoine Pitrou | 41032a6 | 2011-10-27 23:56:55 +0200 | [diff] [blame] | 123 | transport when this error is encountered. |
| 124 | |
| 125 | .. versionadded:: 3.3 |
| 126 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 127 | .. exception:: CertificateError |
| 128 | |
| 129 | Raised to signal an error with a certificate (such as mismatching |
| 130 | hostname). Certificate errors detected by OpenSSL, though, raise |
| 131 | an :exc:`SSLError`. |
| 132 | |
| 133 | |
| 134 | Socket creation |
| 135 | ^^^^^^^^^^^^^^^ |
| 136 | |
| 137 | The following function allows for standalone socket creation. Starting from |
| 138 | Python 3.2, it can be more flexible to use :meth:`SSLContext.wrap_socket` |
| 139 | instead. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 140 | |
Antoine Pitrou | 2d9cb9c | 2010-04-17 17:40:45 +0000 | [diff] [blame] | 141 | .. function:: wrap_socket(sock, keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ssl_version={see docs}, ca_certs=None, do_handshake_on_connect=True, suppress_ragged_eofs=True, ciphers=None) |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 142 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 143 | Takes an instance ``sock`` of :class:`socket.socket`, and returns an instance |
| 144 | of :class:`ssl.SSLSocket`, a subtype of :class:`socket.socket`, which wraps |
Antoine Pitrou | 3e86ba4 | 2013-12-28 17:26:33 +0100 | [diff] [blame] | 145 | the underlying socket in an SSL context. ``sock`` must be a |
| 146 | :data:`~socket.SOCK_STREAM` socket; other socket types are unsupported. |
| 147 | |
| 148 | For client-side sockets, the context construction is lazy; if the |
| 149 | underlying socket isn't connected yet, the context construction will be |
| 150 | performed after :meth:`connect` is called on the socket. For |
| 151 | server-side sockets, if the socket has no remote peer, it is assumed |
| 152 | to be a listening socket, and the server-side SSL wrapping is |
| 153 | automatically performed on client connections accepted via the |
| 154 | :meth:`accept` method. :func:`wrap_socket` may raise :exc:`SSLError`. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 155 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 156 | The ``keyfile`` and ``certfile`` parameters specify optional files which |
| 157 | contain a certificate to be used to identify the local side of the |
| 158 | connection. See the discussion of :ref:`ssl-certificates` for more |
| 159 | information on how the certificate is stored in the ``certfile``. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 160 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 161 | The parameter ``server_side`` is a boolean which identifies whether |
| 162 | server-side or client-side behavior is desired from this socket. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 163 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 164 | The parameter ``cert_reqs`` specifies whether a certificate is required from |
| 165 | the other side of the connection, and whether it will be validated if |
| 166 | provided. It must be one of the three values :const:`CERT_NONE` |
| 167 | (certificates ignored), :const:`CERT_OPTIONAL` (not required, but validated |
| 168 | if provided), or :const:`CERT_REQUIRED` (required and validated). If the |
| 169 | value of this parameter is not :const:`CERT_NONE`, then the ``ca_certs`` |
| 170 | parameter must point to a file of CA certificates. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 171 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 172 | The ``ca_certs`` file contains a set of concatenated "certification |
| 173 | authority" certificates, which are used to validate certificates passed from |
| 174 | the other end of the connection. See the discussion of |
| 175 | :ref:`ssl-certificates` for more information about how to arrange the |
| 176 | certificates in this file. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 177 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 178 | The parameter ``ssl_version`` specifies which version of the SSL protocol to |
| 179 | use. Typically, the server chooses a particular protocol version, and the |
| 180 | client must adapt to the server's choice. Most of the versions are not |
Antoine Pitrou | 84a2edc | 2012-01-09 21:35:11 +0100 | [diff] [blame] | 181 | interoperable with the other versions. If not specified, the default is |
| 182 | :data:`PROTOCOL_SSLv23`; it provides the most compatibility with other |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 183 | versions. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 184 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 185 | Here's a table showing which versions in a client (down the side) can connect |
| 186 | to which versions in a server (along the top): |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 187 | |
| 188 | .. table:: |
| 189 | |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 190 | ======================== ========= ========= ========== ========= =========== =========== |
| 191 | *client* / **server** **SSLv2** **SSLv3** **SSLv23** **TLSv1** **TLSv1.1** **TLSv1.2** |
| 192 | ------------------------ --------- --------- ---------- --------- ----------- ----------- |
| 193 | *SSLv2* yes no yes no no no |
| 194 | *SSLv3* no yes yes no no no |
| 195 | *SSLv23* yes no yes no no no |
| 196 | *TLSv1* no no yes yes no no |
| 197 | *TLSv1.1* no no yes no yes no |
| 198 | *TLSv1.2* no no yes no no yes |
| 199 | ======================== ========= ========= ========== ========= =========== =========== |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 200 | |
Antoine Pitrou | 2d9cb9c | 2010-04-17 17:40:45 +0000 | [diff] [blame] | 201 | .. note:: |
| 202 | |
Benjamin Peterson | d7c3ed5 | 2010-06-27 22:32:30 +0000 | [diff] [blame] | 203 | Which connections succeed will vary depending on the version of |
| 204 | OpenSSL. For instance, in some older versions of OpenSSL (such |
| 205 | as 0.9.7l on OS X 10.4), an SSLv2 client could not connect to an |
| 206 | SSLv23 server. Another example: beginning with OpenSSL 1.0.0, |
| 207 | an SSLv23 client will not actually attempt SSLv2 connections |
| 208 | unless you explicitly enable SSLv2 ciphers; for example, you |
| 209 | might specify ``"ALL"`` or ``"SSLv2"`` as the *ciphers* parameter |
| 210 | to enable them. |
Antoine Pitrou | 2d9cb9c | 2010-04-17 17:40:45 +0000 | [diff] [blame] | 211 | |
Benjamin Peterson | d7c3ed5 | 2010-06-27 22:32:30 +0000 | [diff] [blame] | 212 | The *ciphers* parameter sets the available ciphers for this SSL object. |
Antoine Pitrou | 2d9cb9c | 2010-04-17 17:40:45 +0000 | [diff] [blame] | 213 | It should be a string in the `OpenSSL cipher list format |
| 214 | <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`_. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 215 | |
Bill Janssen | 48dc27c | 2007-12-05 03:38:10 +0000 | [diff] [blame] | 216 | The parameter ``do_handshake_on_connect`` specifies whether to do the SSL |
| 217 | handshake automatically after doing a :meth:`socket.connect`, or whether the |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 218 | application program will call it explicitly, by invoking the |
| 219 | :meth:`SSLSocket.do_handshake` method. Calling |
| 220 | :meth:`SSLSocket.do_handshake` explicitly gives the program control over the |
| 221 | blocking behavior of the socket I/O involved in the handshake. |
Bill Janssen | 48dc27c | 2007-12-05 03:38:10 +0000 | [diff] [blame] | 222 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 223 | The parameter ``suppress_ragged_eofs`` specifies how the |
Antoine Pitrou | dab6426 | 2010-09-19 13:31:06 +0000 | [diff] [blame] | 224 | :meth:`SSLSocket.recv` method should signal unexpected EOF from the other end |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 225 | of the connection. If specified as :const:`True` (the default), it returns a |
Antoine Pitrou | dab6426 | 2010-09-19 13:31:06 +0000 | [diff] [blame] | 226 | normal EOF (an empty bytes object) in response to unexpected EOF errors |
| 227 | raised from the underlying socket; if :const:`False`, it will raise the |
| 228 | exceptions back to the caller. |
Bill Janssen | 48dc27c | 2007-12-05 03:38:10 +0000 | [diff] [blame] | 229 | |
Ezio Melotti | 4d5195b | 2010-04-20 10:57:44 +0000 | [diff] [blame] | 230 | .. versionchanged:: 3.2 |
Antoine Pitrou | 2d9cb9c | 2010-04-17 17:40:45 +0000 | [diff] [blame] | 231 | New optional argument *ciphers*. |
| 232 | |
Antoine Pitrou | 5bef410 | 2013-11-23 16:16:29 +0100 | [diff] [blame] | 233 | |
| 234 | Context creation |
| 235 | ^^^^^^^^^^^^^^^^ |
| 236 | |
| 237 | A convenience function helps create :class:`SSLContext` objects for common |
| 238 | purposes. |
| 239 | |
| 240 | .. function:: create_default_context(purpose=Purpose.SERVER_AUTH, cafile=None, capath=None, cadata=None) |
| 241 | |
| 242 | Return a new :class:`SSLContext` object with default settings for |
| 243 | the given *purpose*. The settings are chosen by the :mod:`ssl` module, |
| 244 | and usually represent a higher security level than when calling the |
| 245 | :class:`SSLContext` constructor directly. |
| 246 | |
| 247 | *cafile*, *capath*, *cadata* represent optional CA certificates to |
| 248 | trust for certificate verification, as in |
| 249 | :meth:`SSLContext.load_verify_locations`. If all three are |
| 250 | :const:`None`, this function can choose to trust the system's default |
| 251 | CA certificates instead. |
| 252 | |
Donald Stufft | 6a2ba94 | 2014-03-23 19:05:28 -0400 | [diff] [blame] | 253 | The settings in Python 3.4 are: :data:`PROTOCOL_SSLv23`, :data:`OP_NO_SSLv2`, |
| 254 | and :data:`OP_NO_SSLv3` with high encryption cipher suites without RC4 and |
| 255 | without unauthenticated cipher suites. Passing :data:`~Purpose.SERVER_AUTH` |
| 256 | as *purpose* sets :data:`~SSLContext.verify_mode` to :data:`CERT_REQUIRED` |
| 257 | and either loads CA certificates (when at least one of *cafile*, *capath* or |
| 258 | *cadata* is given) or uses :meth:`SSLContext.load_default_certs` to load |
| 259 | default CA certificates. |
Antoine Pitrou | 5bef410 | 2013-11-23 16:16:29 +0100 | [diff] [blame] | 260 | |
| 261 | .. note:: |
| 262 | The protocol, options, cipher and other settings may change to more |
| 263 | restrictive values anytime without prior deprecation. The values |
| 264 | represent a fair balance between compatibility and security. |
| 265 | |
| 266 | If your application needs specific settings, you should create a |
| 267 | :class:`SSLContext` and apply the settings yourself. |
| 268 | |
Donald Stufft | 6a2ba94 | 2014-03-23 19:05:28 -0400 | [diff] [blame] | 269 | .. note:: |
| 270 | If you find that when certain older clients or servers attempt to connect |
| 271 | with a :class:`SSLContext` created by this function that they get an |
| 272 | error stating "Protocol or cipher suite mismatch", it may be that they |
| 273 | only support SSL3.0 which this function excludes using the |
| 274 | :data:`OP_NO_SSLv3`. SSL3.0 has problematic security due to a number of |
| 275 | poor implementations and it's reliance on MD5 within the protocol. If you |
| 276 | wish to continue to use this function but still allow SSL 3.0 connections |
| 277 | you can re-enable them using:: |
| 278 | |
| 279 | ctx = ssl.create_default_context(Purpose.CLIENT_AUTH) |
| 280 | ctx.options &= ~ssl.OP_NO_SSLv3 |
| 281 | |
Antoine Pitrou | 5bef410 | 2013-11-23 16:16:29 +0100 | [diff] [blame] | 282 | .. versionadded:: 3.4 |
| 283 | |
| 284 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 285 | Random generation |
| 286 | ^^^^^^^^^^^^^^^^^ |
| 287 | |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 288 | .. function:: RAND_bytes(num) |
| 289 | |
Victor Stinner | a675206 | 2011-05-25 11:27:40 +0200 | [diff] [blame] | 290 | Returns *num* cryptographically strong pseudo-random bytes. Raises an |
| 291 | :class:`SSLError` if the PRNG has not been seeded with enough data or if the |
| 292 | operation is not supported by the current RAND method. :func:`RAND_status` |
| 293 | can be used to check the status of the PRNG and :func:`RAND_add` can be used |
| 294 | to seed the PRNG. |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 295 | |
Victor Stinner | 19fb53c | 2011-05-24 21:32:40 +0200 | [diff] [blame] | 296 | Read the Wikipedia article, `Cryptographically secure pseudorandom number |
Victor Stinner | a675206 | 2011-05-25 11:27:40 +0200 | [diff] [blame] | 297 | generator (CSPRNG) |
Victor Stinner | 19fb53c | 2011-05-24 21:32:40 +0200 | [diff] [blame] | 298 | <http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator>`_, |
| 299 | to get the requirements of a cryptographically generator. |
| 300 | |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 301 | .. versionadded:: 3.3 |
| 302 | |
| 303 | .. function:: RAND_pseudo_bytes(num) |
| 304 | |
| 305 | Returns (bytes, is_cryptographic): bytes are *num* pseudo-random bytes, |
Serhiy Storchaka | fbc1c26 | 2013-11-29 12:17:13 +0200 | [diff] [blame] | 306 | is_cryptographic is ``True`` if the bytes generated are cryptographically |
Victor Stinner | a675206 | 2011-05-25 11:27:40 +0200 | [diff] [blame] | 307 | strong. Raises an :class:`SSLError` if the operation is not supported by the |
| 308 | current RAND method. |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 309 | |
Victor Stinner | 19fb53c | 2011-05-24 21:32:40 +0200 | [diff] [blame] | 310 | Generated pseudo-random byte sequences will be unique if they are of |
| 311 | sufficient length, but are not necessarily unpredictable. They can be used |
| 312 | for non-cryptographic purposes and for certain purposes in cryptographic |
| 313 | protocols, but usually not for key generation etc. |
| 314 | |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 315 | .. versionadded:: 3.3 |
| 316 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 317 | .. function:: RAND_status() |
| 318 | |
Serhiy Storchaka | fbc1c26 | 2013-11-29 12:17:13 +0200 | [diff] [blame] | 319 | Returns ``True`` if the SSL pseudo-random number generator has been seeded with |
| 320 | 'enough' randomness, and ``False`` otherwise. You can use :func:`ssl.RAND_egd` |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 321 | and :func:`ssl.RAND_add` to increase the randomness of the pseudo-random |
| 322 | number generator. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 323 | |
| 324 | .. function:: RAND_egd(path) |
| 325 | |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 326 | If you are running an entropy-gathering daemon (EGD) somewhere, and *path* |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 327 | is the pathname of a socket connection open to it, this will read 256 bytes |
| 328 | of randomness from the socket, and add it to the SSL pseudo-random number |
| 329 | generator to increase the security of generated secret keys. This is |
| 330 | typically only necessary on systems without better sources of randomness. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 331 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 332 | See http://egd.sourceforge.net/ or http://prngd.sourceforge.net/ for sources |
| 333 | of entropy-gathering daemons. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 334 | |
| 335 | .. function:: RAND_add(bytes, entropy) |
| 336 | |
Victor Stinner | 99c8b16 | 2011-05-24 12:05:19 +0200 | [diff] [blame] | 337 | Mixes the given *bytes* into the SSL pseudo-random number generator. The |
| 338 | parameter *entropy* (a float) is a lower bound on the entropy contained in |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 339 | string (so you can always use :const:`0.0`). See :rfc:`1750` for more |
| 340 | information on sources of entropy. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 341 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 342 | Certificate handling |
| 343 | ^^^^^^^^^^^^^^^^^^^^ |
| 344 | |
| 345 | .. function:: match_hostname(cert, hostname) |
| 346 | |
| 347 | Verify that *cert* (in decoded format as returned by |
| 348 | :meth:`SSLSocket.getpeercert`) matches the given *hostname*. The rules |
| 349 | applied are those for checking the identity of HTTPS servers as outlined |
Georg Brandl | 72c98d3 | 2013-10-27 07:16:53 +0100 | [diff] [blame] | 350 | in :rfc:`2818` and :rfc:`6125`, except that IP addresses are not currently |
| 351 | supported. In addition to HTTPS, this function should be suitable for |
| 352 | checking the identity of servers in various SSL-based protocols such as |
| 353 | FTPS, IMAPS, POPS and others. |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 354 | |
| 355 | :exc:`CertificateError` is raised on failure. On success, the function |
| 356 | returns nothing:: |
| 357 | |
| 358 | >>> cert = {'subject': ((('commonName', 'example.com'),),)} |
| 359 | >>> ssl.match_hostname(cert, "example.com") |
| 360 | >>> ssl.match_hostname(cert, "example.org") |
| 361 | Traceback (most recent call last): |
| 362 | File "<stdin>", line 1, in <module> |
| 363 | File "/home/py3k/Lib/ssl.py", line 130, in match_hostname |
| 364 | ssl.CertificateError: hostname 'example.org' doesn't match 'example.com' |
| 365 | |
| 366 | .. versionadded:: 3.2 |
| 367 | |
Georg Brandl | 72c98d3 | 2013-10-27 07:16:53 +0100 | [diff] [blame] | 368 | .. versionchanged:: 3.3.3 |
| 369 | The function now follows :rfc:`6125`, section 6.4.3 and does neither |
| 370 | match multiple wildcards (e.g. ``*.*.com`` or ``*a*.example.org``) nor |
| 371 | a wildcard inside an internationalized domain names (IDN) fragment. |
| 372 | IDN A-labels such as ``www*.xn--pthon-kva.org`` are still supported, |
| 373 | but ``x*.python.org`` no longer matches ``xn--tda.python.org``. |
| 374 | |
Antoine Pitrou | c695c95 | 2014-04-28 20:57:36 +0200 | [diff] [blame] | 375 | .. function:: cert_time_to_seconds(cert_time) |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 376 | |
Antoine Pitrou | c695c95 | 2014-04-28 20:57:36 +0200 | [diff] [blame] | 377 | Return the time in seconds since the Epoch, given the ``cert_time`` |
| 378 | string representing the "notBefore" or "notAfter" date from a |
| 379 | certificate in ``"%b %d %H:%M:%S %Y %Z"`` strptime format (C |
| 380 | locale). |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 381 | |
Antoine Pitrou | c695c95 | 2014-04-28 20:57:36 +0200 | [diff] [blame] | 382 | Here's an example: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 383 | |
Antoine Pitrou | c695c95 | 2014-04-28 20:57:36 +0200 | [diff] [blame] | 384 | .. doctest:: newcontext |
| 385 | |
| 386 | >>> import ssl |
| 387 | >>> timestamp = ssl.cert_time_to_seconds("Jan 5 09:34:43 2018 GMT") |
| 388 | >>> timestamp |
| 389 | 1515144883 |
| 390 | >>> from datetime import datetime |
| 391 | >>> print(datetime.utcfromtimestamp(timestamp)) |
| 392 | 2018-01-05 09:34:43 |
| 393 | |
| 394 | "notBefore" or "notAfter" dates must use GMT (:rfc:`5280`). |
| 395 | |
| 396 | .. versionchanged:: 3.5 |
| 397 | Interpret the input time as a time in UTC as specified by 'GMT' |
| 398 | timezone in the input string. Local timezone was used |
| 399 | previously. Return an integer (no fractions of a second in the |
| 400 | input format) |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 401 | |
Antoine Pitrou | 94a5b66 | 2014-04-16 18:56:28 +0200 | [diff] [blame] | 402 | .. function:: get_server_certificate(addr, ssl_version=PROTOCOL_SSLv23, ca_certs=None) |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 403 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 404 | Given the address ``addr`` of an SSL-protected server, as a (*hostname*, |
| 405 | *port-number*) pair, fetches the server's certificate, and returns it as a |
| 406 | PEM-encoded string. If ``ssl_version`` is specified, uses that version of |
| 407 | the SSL protocol to attempt to connect to the server. If ``ca_certs`` is |
| 408 | specified, it should be a file containing a list of root certificates, the |
| 409 | same format as used for the same parameter in :func:`wrap_socket`. The call |
| 410 | will attempt to validate the server certificate against that set of root |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 411 | certificates, and will fail if the validation attempt fails. |
| 412 | |
Antoine Pitrou | 15399c3 | 2011-04-28 19:23:55 +0200 | [diff] [blame] | 413 | .. versionchanged:: 3.3 |
| 414 | This function is now IPv6-compatible. |
| 415 | |
Antoine Pitrou | 94a5b66 | 2014-04-16 18:56:28 +0200 | [diff] [blame] | 416 | .. versionchanged:: 3.5 |
| 417 | The default *ssl_version* is changed from :data:`PROTOCOL_SSLv3` to |
| 418 | :data:`PROTOCOL_SSLv23` for maximum compatibility with modern servers. |
| 419 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 420 | .. function:: DER_cert_to_PEM_cert(DER_cert_bytes) |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 421 | |
| 422 | Given a certificate as a DER-encoded blob of bytes, returns a PEM-encoded |
| 423 | string version of the same certificate. |
| 424 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 425 | .. function:: PEM_cert_to_DER_cert(PEM_cert_string) |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 426 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 427 | Given a certificate as an ASCII PEM string, returns a DER-encoded sequence of |
| 428 | bytes for that same certificate. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 429 | |
Christian Heimes | 6d7ad13 | 2013-06-09 18:02:55 +0200 | [diff] [blame] | 430 | .. function:: get_default_verify_paths() |
| 431 | |
| 432 | Returns a named tuple with paths to OpenSSL's default cafile and capath. |
| 433 | The paths are the same as used by |
| 434 | :meth:`SSLContext.set_default_verify_paths`. The return value is a |
| 435 | :term:`named tuple` ``DefaultVerifyPaths``: |
| 436 | |
| 437 | * :attr:`cafile` - resolved path to cafile or None if the file doesn't exist, |
| 438 | * :attr:`capath` - resolved path to capath or None if the directory doesn't exist, |
| 439 | * :attr:`openssl_cafile_env` - OpenSSL's environment key that points to a cafile, |
| 440 | * :attr:`openssl_cafile` - hard coded path to a cafile, |
| 441 | * :attr:`openssl_capath_env` - OpenSSL's environment key that points to a capath, |
| 442 | * :attr:`openssl_capath` - hard coded path to a capath directory |
| 443 | |
| 444 | .. versionadded:: 3.4 |
| 445 | |
Christian Heimes | 44109d7 | 2013-11-22 01:51:30 +0100 | [diff] [blame] | 446 | .. function:: enum_certificates(store_name) |
Christian Heimes | 46bebee | 2013-06-09 19:03:31 +0200 | [diff] [blame] | 447 | |
| 448 | Retrieve certificates from Windows' system cert store. *store_name* may be |
| 449 | one of ``CA``, ``ROOT`` or ``MY``. Windows may provide additional cert |
Christian Heimes | 44109d7 | 2013-11-22 01:51:30 +0100 | [diff] [blame] | 450 | stores, too. |
Christian Heimes | 46bebee | 2013-06-09 19:03:31 +0200 | [diff] [blame] | 451 | |
Christian Heimes | 44109d7 | 2013-11-22 01:51:30 +0100 | [diff] [blame] | 452 | The function returns a list of (cert_bytes, encoding_type, trust) tuples. |
| 453 | The encoding_type specifies the encoding of cert_bytes. It is either |
| 454 | :const:`x509_asn` for X.509 ASN.1 data or :const:`pkcs_7_asn` for |
| 455 | PKCS#7 ASN.1 data. Trust specifies the purpose of the certificate as a set |
| 456 | of OIDS or exactly ``True`` if the certificate is trustworthy for all |
| 457 | purposes. |
| 458 | |
| 459 | Example:: |
| 460 | |
| 461 | >>> ssl.enum_certificates("CA") |
| 462 | [(b'data...', 'x509_asn', {'1.3.6.1.5.5.7.3.1', '1.3.6.1.5.5.7.3.2'}), |
| 463 | (b'data...', 'x509_asn', True)] |
Christian Heimes | 46bebee | 2013-06-09 19:03:31 +0200 | [diff] [blame] | 464 | |
| 465 | Availability: Windows. |
| 466 | |
| 467 | .. versionadded:: 3.4 |
Christian Heimes | 6d7ad13 | 2013-06-09 18:02:55 +0200 | [diff] [blame] | 468 | |
Christian Heimes | 44109d7 | 2013-11-22 01:51:30 +0100 | [diff] [blame] | 469 | .. function:: enum_crls(store_name) |
| 470 | |
| 471 | Retrieve CRLs from Windows' system cert store. *store_name* may be |
| 472 | one of ``CA``, ``ROOT`` or ``MY``. Windows may provide additional cert |
| 473 | stores, too. |
| 474 | |
| 475 | The function returns a list of (cert_bytes, encoding_type, trust) tuples. |
| 476 | The encoding_type specifies the encoding of cert_bytes. It is either |
| 477 | :const:`x509_asn` for X.509 ASN.1 data or :const:`pkcs_7_asn` for |
| 478 | PKCS#7 ASN.1 data. |
| 479 | |
| 480 | Availability: Windows. |
| 481 | |
| 482 | .. versionadded:: 3.4 |
| 483 | |
| 484 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 485 | Constants |
| 486 | ^^^^^^^^^ |
| 487 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 488 | .. data:: CERT_NONE |
| 489 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 490 | Possible value for :attr:`SSLContext.verify_mode`, or the ``cert_reqs`` |
| 491 | parameter to :func:`wrap_socket`. In this mode (the default), no |
| 492 | certificates will be required from the other side of the socket connection. |
| 493 | If a certificate is received from the other end, no attempt to validate it |
| 494 | is made. |
| 495 | |
| 496 | See the discussion of :ref:`ssl-security` below. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 497 | |
| 498 | .. data:: CERT_OPTIONAL |
| 499 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 500 | Possible value for :attr:`SSLContext.verify_mode`, or the ``cert_reqs`` |
| 501 | parameter to :func:`wrap_socket`. In this mode no certificates will be |
| 502 | required from the other side of the socket connection; but if they |
| 503 | are provided, validation will be attempted and an :class:`SSLError` |
| 504 | will be raised on failure. |
| 505 | |
| 506 | Use of this setting requires a valid set of CA certificates to |
| 507 | be passed, either to :meth:`SSLContext.load_verify_locations` or as a |
| 508 | value of the ``ca_certs`` parameter to :func:`wrap_socket`. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 509 | |
| 510 | .. data:: CERT_REQUIRED |
| 511 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 512 | Possible value for :attr:`SSLContext.verify_mode`, or the ``cert_reqs`` |
| 513 | parameter to :func:`wrap_socket`. In this mode, certificates are |
| 514 | required from the other side of the socket connection; an :class:`SSLError` |
| 515 | will be raised if no certificate is provided, or if its validation fails. |
| 516 | |
| 517 | Use of this setting requires a valid set of CA certificates to |
| 518 | be passed, either to :meth:`SSLContext.load_verify_locations` or as a |
| 519 | value of the ``ca_certs`` parameter to :func:`wrap_socket`. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 520 | |
Christian Heimes | 2258779 | 2013-11-21 23:56:13 +0100 | [diff] [blame] | 521 | .. data:: VERIFY_DEFAULT |
| 522 | |
| 523 | Possible value for :attr:`SSLContext.verify_flags`. In this mode, |
| 524 | certificate revocation lists (CRLs) are not checked. By default OpenSSL |
| 525 | does neither require nor verify CRLs. |
| 526 | |
| 527 | .. versionadded:: 3.4 |
| 528 | |
| 529 | .. data:: VERIFY_CRL_CHECK_LEAF |
| 530 | |
| 531 | Possible value for :attr:`SSLContext.verify_flags`. In this mode, only the |
| 532 | peer cert is check but non of the intermediate CA certificates. The mode |
| 533 | requires a valid CRL that is signed by the peer cert's issuer (its direct |
| 534 | ancestor CA). If no proper has been loaded |
| 535 | :attr:`SSLContext.load_verify_locations`, validation will fail. |
| 536 | |
| 537 | .. versionadded:: 3.4 |
| 538 | |
| 539 | .. data:: VERIFY_CRL_CHECK_CHAIN |
| 540 | |
| 541 | Possible value for :attr:`SSLContext.verify_flags`. In this mode, CRLs of |
| 542 | all certificates in the peer cert chain are checked. |
| 543 | |
| 544 | .. versionadded:: 3.4 |
| 545 | |
| 546 | .. data:: VERIFY_X509_STRICT |
| 547 | |
| 548 | Possible value for :attr:`SSLContext.verify_flags` to disable workarounds |
| 549 | for broken X.509 certificates. |
| 550 | |
| 551 | .. versionadded:: 3.4 |
| 552 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 553 | .. data:: PROTOCOL_SSLv2 |
| 554 | |
| 555 | Selects SSL version 2 as the channel encryption protocol. |
| 556 | |
Victor Stinner | 3de4919 | 2011-05-09 00:42:58 +0200 | [diff] [blame] | 557 | This protocol is not available if OpenSSL is compiled with OPENSSL_NO_SSL2 |
| 558 | flag. |
| 559 | |
Antoine Pitrou | 8eac60d | 2010-05-16 14:19:41 +0000 | [diff] [blame] | 560 | .. warning:: |
| 561 | |
| 562 | SSL version 2 is insecure. Its use is highly discouraged. |
| 563 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 564 | .. data:: PROTOCOL_SSLv23 |
| 565 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 566 | Selects SSL version 2 or 3 as the channel encryption protocol. This is a |
| 567 | setting to use with servers for maximum compatibility with the other end of |
| 568 | an SSL connection, but it may cause the specific ciphers chosen for the |
| 569 | encryption to be of fairly low quality. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 570 | |
| 571 | .. data:: PROTOCOL_SSLv3 |
| 572 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 573 | Selects SSL version 3 as the channel encryption protocol. For clients, this |
| 574 | is the maximally compatible SSL variant. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 575 | |
| 576 | .. data:: PROTOCOL_TLSv1 |
| 577 | |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 578 | Selects TLS version 1.0 as the channel encryption protocol. |
| 579 | |
| 580 | .. data:: PROTOCOL_TLSv1_1 |
| 581 | |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 582 | Selects TLS version 1.1 as the channel encryption protocol. |
| 583 | Available only with openssl version 1.0.1+. |
| 584 | |
| 585 | .. versionadded:: 3.4 |
| 586 | |
| 587 | .. data:: PROTOCOL_TLSv1_2 |
| 588 | |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 589 | Selects TLS version 1.2 as the channel encryption protocol. This is the most |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 590 | modern version, and probably the best choice for maximum protection, if both |
R David Murray | 748bad2 | 2013-12-20 17:08:39 -0500 | [diff] [blame] | 591 | sides can speak it. Available only with openssl version 1.0.1+. |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 592 | |
| 593 | .. versionadded:: 3.4 |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 594 | |
Antoine Pitrou | b521877 | 2010-05-21 09:56:06 +0000 | [diff] [blame] | 595 | .. data:: OP_ALL |
| 596 | |
| 597 | Enables workarounds for various bugs present in other SSL implementations. |
Antoine Pitrou | 9f6b02e | 2012-01-27 10:02:55 +0100 | [diff] [blame] | 598 | This option is set by default. It does not necessarily set the same |
| 599 | flags as OpenSSL's ``SSL_OP_ALL`` constant. |
Antoine Pitrou | b521877 | 2010-05-21 09:56:06 +0000 | [diff] [blame] | 600 | |
| 601 | .. versionadded:: 3.2 |
| 602 | |
| 603 | .. data:: OP_NO_SSLv2 |
| 604 | |
| 605 | Prevents an SSLv2 connection. This option is only applicable in |
| 606 | conjunction with :const:`PROTOCOL_SSLv23`. It prevents the peers from |
| 607 | choosing SSLv2 as the protocol version. |
| 608 | |
| 609 | .. versionadded:: 3.2 |
| 610 | |
| 611 | .. data:: OP_NO_SSLv3 |
| 612 | |
| 613 | Prevents an SSLv3 connection. This option is only applicable in |
| 614 | conjunction with :const:`PROTOCOL_SSLv23`. It prevents the peers from |
| 615 | choosing SSLv3 as the protocol version. |
| 616 | |
| 617 | .. versionadded:: 3.2 |
| 618 | |
| 619 | .. data:: OP_NO_TLSv1 |
| 620 | |
| 621 | Prevents a TLSv1 connection. This option is only applicable in |
| 622 | conjunction with :const:`PROTOCOL_SSLv23`. It prevents the peers from |
| 623 | choosing TLSv1 as the protocol version. |
| 624 | |
| 625 | .. versionadded:: 3.2 |
| 626 | |
Antoine Pitrou | 2463e5f | 2013-03-28 22:24:43 +0100 | [diff] [blame] | 627 | .. data:: OP_NO_TLSv1_1 |
| 628 | |
| 629 | Prevents a TLSv1.1 connection. This option is only applicable in conjunction |
| 630 | with :const:`PROTOCOL_SSLv23`. It prevents the peers from choosing TLSv1.1 as |
| 631 | the protocol version. Available only with openssl version 1.0.1+. |
| 632 | |
| 633 | .. versionadded:: 3.4 |
| 634 | |
| 635 | .. data:: OP_NO_TLSv1_2 |
| 636 | |
| 637 | Prevents a TLSv1.2 connection. This option is only applicable in conjunction |
| 638 | with :const:`PROTOCOL_SSLv23`. It prevents the peers from choosing TLSv1.2 as |
| 639 | the protocol version. Available only with openssl version 1.0.1+. |
| 640 | |
| 641 | .. versionadded:: 3.4 |
| 642 | |
Antoine Pitrou | 6db4944 | 2011-12-19 13:27:11 +0100 | [diff] [blame] | 643 | .. data:: OP_CIPHER_SERVER_PREFERENCE |
| 644 | |
| 645 | Use the server's cipher ordering preference, rather than the client's. |
| 646 | This option has no effect on client sockets and SSLv2 server sockets. |
| 647 | |
| 648 | .. versionadded:: 3.3 |
| 649 | |
Antoine Pitrou | 0e576f1 | 2011-12-22 10:03:38 +0100 | [diff] [blame] | 650 | .. data:: OP_SINGLE_DH_USE |
| 651 | |
| 652 | Prevents re-use of the same DH key for distinct SSL sessions. This |
| 653 | improves forward secrecy but requires more computational resources. |
| 654 | This option only applies to server sockets. |
| 655 | |
| 656 | .. versionadded:: 3.3 |
| 657 | |
Antoine Pitrou | 923df6f | 2011-12-19 17:16:51 +0100 | [diff] [blame] | 658 | .. data:: OP_SINGLE_ECDH_USE |
| 659 | |
Antoine Pitrou | 0e576f1 | 2011-12-22 10:03:38 +0100 | [diff] [blame] | 660 | Prevents re-use of the same ECDH key for distinct SSL sessions. This |
Antoine Pitrou | 923df6f | 2011-12-19 17:16:51 +0100 | [diff] [blame] | 661 | improves forward secrecy but requires more computational resources. |
| 662 | This option only applies to server sockets. |
| 663 | |
| 664 | .. versionadded:: 3.3 |
| 665 | |
Antoine Pitrou | 8abdb8a | 2011-12-20 10:13:40 +0100 | [diff] [blame] | 666 | .. data:: OP_NO_COMPRESSION |
| 667 | |
| 668 | Disable compression on the SSL channel. This is useful if the application |
| 669 | protocol supports its own compression scheme. |
| 670 | |
| 671 | This option is only available with OpenSSL 1.0.0 and later. |
| 672 | |
| 673 | .. versionadded:: 3.3 |
| 674 | |
Antoine Pitrou | 501da61 | 2011-12-21 09:27:41 +0100 | [diff] [blame] | 675 | .. data:: HAS_ECDH |
| 676 | |
| 677 | Whether the OpenSSL library has built-in support for Elliptic Curve-based |
| 678 | Diffie-Hellman key exchange. This should be true unless the feature was |
| 679 | explicitly disabled by the distributor. |
| 680 | |
| 681 | .. versionadded:: 3.3 |
| 682 | |
Antoine Pitrou | d532321 | 2010-10-22 18:19:07 +0000 | [diff] [blame] | 683 | .. data:: HAS_SNI |
| 684 | |
| 685 | Whether the OpenSSL library has built-in support for the *Server Name |
| 686 | Indication* extension to the SSLv3 and TLSv1 protocols (as defined in |
| 687 | :rfc:`4366`). When true, you can use the *server_hostname* argument to |
| 688 | :meth:`SSLContext.wrap_socket`. |
| 689 | |
| 690 | .. versionadded:: 3.2 |
| 691 | |
Antoine Pitrou | d5d17eb | 2012-03-22 00:23:03 +0100 | [diff] [blame] | 692 | .. data:: HAS_NPN |
| 693 | |
| 694 | Whether the OpenSSL library has built-in support for *Next Protocol |
| 695 | Negotiation* as described in the `NPN draft specification |
| 696 | <http://tools.ietf.org/html/draft-agl-tls-nextprotoneg>`_. When true, |
| 697 | you can use the :meth:`SSLContext.set_npn_protocols` method to advertise |
| 698 | which protocols you want to support. |
| 699 | |
| 700 | .. versionadded:: 3.3 |
| 701 | |
Antoine Pitrou | d649480 | 2011-07-21 01:11:30 +0200 | [diff] [blame] | 702 | .. data:: CHANNEL_BINDING_TYPES |
| 703 | |
| 704 | List of supported TLS channel binding types. Strings in this list |
| 705 | can be used as arguments to :meth:`SSLSocket.get_channel_binding`. |
| 706 | |
| 707 | .. versionadded:: 3.3 |
| 708 | |
Antoine Pitrou | 04f6a32 | 2010-04-05 21:40:07 +0000 | [diff] [blame] | 709 | .. data:: OPENSSL_VERSION |
| 710 | |
| 711 | The version string of the OpenSSL library loaded by the interpreter:: |
| 712 | |
| 713 | >>> ssl.OPENSSL_VERSION |
| 714 | 'OpenSSL 0.9.8k 25 Mar 2009' |
| 715 | |
Antoine Pitrou | 43a94c31 | 2010-04-05 21:44:48 +0000 | [diff] [blame] | 716 | .. versionadded:: 3.2 |
Antoine Pitrou | 04f6a32 | 2010-04-05 21:40:07 +0000 | [diff] [blame] | 717 | |
| 718 | .. data:: OPENSSL_VERSION_INFO |
| 719 | |
| 720 | A tuple of five integers representing version information about the |
| 721 | OpenSSL library:: |
| 722 | |
| 723 | >>> ssl.OPENSSL_VERSION_INFO |
| 724 | (0, 9, 8, 11, 15) |
| 725 | |
Antoine Pitrou | 43a94c31 | 2010-04-05 21:44:48 +0000 | [diff] [blame] | 726 | .. versionadded:: 3.2 |
Antoine Pitrou | 04f6a32 | 2010-04-05 21:40:07 +0000 | [diff] [blame] | 727 | |
| 728 | .. data:: OPENSSL_VERSION_NUMBER |
| 729 | |
| 730 | The raw version number of the OpenSSL library, as a single integer:: |
| 731 | |
| 732 | >>> ssl.OPENSSL_VERSION_NUMBER |
Antoine Pitrou | 43a94c31 | 2010-04-05 21:44:48 +0000 | [diff] [blame] | 733 | 9470143 |
Antoine Pitrou | 04f6a32 | 2010-04-05 21:40:07 +0000 | [diff] [blame] | 734 | >>> hex(ssl.OPENSSL_VERSION_NUMBER) |
Antoine Pitrou | 43a94c31 | 2010-04-05 21:44:48 +0000 | [diff] [blame] | 735 | '0x9080bf' |
Antoine Pitrou | 04f6a32 | 2010-04-05 21:40:07 +0000 | [diff] [blame] | 736 | |
Antoine Pitrou | 43a94c31 | 2010-04-05 21:44:48 +0000 | [diff] [blame] | 737 | .. versionadded:: 3.2 |
Antoine Pitrou | 04f6a32 | 2010-04-05 21:40:07 +0000 | [diff] [blame] | 738 | |
Antoine Pitrou | 58ddc9d | 2013-01-05 21:20:29 +0100 | [diff] [blame] | 739 | .. data:: ALERT_DESCRIPTION_HANDSHAKE_FAILURE |
| 740 | ALERT_DESCRIPTION_INTERNAL_ERROR |
| 741 | ALERT_DESCRIPTION_* |
| 742 | |
| 743 | Alert Descriptions from :rfc:`5246` and others. The `IANA TLS Alert Registry |
| 744 | <http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-6>`_ |
| 745 | contains this list and references to the RFCs where their meaning is defined. |
| 746 | |
| 747 | Used as the return value of the callback function in |
| 748 | :meth:`SSLContext.set_servername_callback`. |
| 749 | |
| 750 | .. versionadded:: 3.4 |
| 751 | |
Christian Heimes | 72d2850 | 2013-11-23 13:56:58 +0100 | [diff] [blame] | 752 | .. data:: Purpose.SERVER_AUTH |
| 753 | |
Antoine Pitrou | 5bef410 | 2013-11-23 16:16:29 +0100 | [diff] [blame] | 754 | Option for :func:`create_default_context` and |
| 755 | :meth:`SSLContext.load_default_certs`. This value indicates that the |
| 756 | context may be used to authenticate Web servers (therefore, it will |
| 757 | be used to create client-side sockets). |
Christian Heimes | 72d2850 | 2013-11-23 13:56:58 +0100 | [diff] [blame] | 758 | |
| 759 | .. versionadded:: 3.4 |
| 760 | |
Christian Heimes | 6b2ff98 | 2013-11-23 14:42:01 +0100 | [diff] [blame] | 761 | .. data:: Purpose.CLIENT_AUTH |
Christian Heimes | 72d2850 | 2013-11-23 13:56:58 +0100 | [diff] [blame] | 762 | |
Antoine Pitrou | 5bef410 | 2013-11-23 16:16:29 +0100 | [diff] [blame] | 763 | Option for :func:`create_default_context` and |
| 764 | :meth:`SSLContext.load_default_certs`. This value indicates that the |
| 765 | context may be used to authenticate Web clients (therefore, it will |
| 766 | be used to create server-side sockets). |
Christian Heimes | 72d2850 | 2013-11-23 13:56:58 +0100 | [diff] [blame] | 767 | |
| 768 | .. versionadded:: 3.4 |
| 769 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 770 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 771 | SSL Sockets |
| 772 | ----------- |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 773 | |
Victor Stinner | 3c3d3c7 | 2014-10-10 12:06:51 +0200 | [diff] [blame] | 774 | .. class:: SSLSocket(socket.socket) |
Antoine Pitrou | 792ff3e | 2010-09-19 13:19:21 +0000 | [diff] [blame] | 775 | |
Victor Stinner | 3c3d3c7 | 2014-10-10 12:06:51 +0200 | [diff] [blame] | 776 | SSL sockets provide the following methods of :ref:`socket-objects`: |
Zachary Ware | ba9fb0d | 2014-06-11 15:02:25 -0500 | [diff] [blame] | 777 | |
Victor Stinner | 3c3d3c7 | 2014-10-10 12:06:51 +0200 | [diff] [blame] | 778 | - :meth:`~socket.socket.accept()` |
| 779 | - :meth:`~socket.socket.bind()` |
| 780 | - :meth:`~socket.socket.close()` |
| 781 | - :meth:`~socket.socket.connect()` |
| 782 | - :meth:`~socket.socket.detach()` |
| 783 | - :meth:`~socket.socket.fileno()` |
| 784 | - :meth:`~socket.socket.getpeername()`, :meth:`~socket.socket.getsockname()` |
| 785 | - :meth:`~socket.socket.getsockopt()`, :meth:`~socket.socket.setsockopt()` |
| 786 | - :meth:`~socket.socket.gettimeout()`, :meth:`~socket.socket.settimeout()`, |
| 787 | :meth:`~socket.socket.setblocking()` |
| 788 | - :meth:`~socket.socket.listen()` |
| 789 | - :meth:`~socket.socket.makefile()` |
| 790 | - :meth:`~socket.socket.recv()`, :meth:`~socket.socket.recv_into()` |
| 791 | (but passing a non-zero ``flags`` argument is not allowed) |
| 792 | - :meth:`~socket.socket.send()`, :meth:`~socket.socket.sendall()` (with |
| 793 | the same limitation) |
Victor Stinner | 92127a5 | 2014-10-10 12:43:17 +0200 | [diff] [blame] | 794 | - :meth:`~socket.socket.sendfile()` (but :mod:`os.sendfile` will be used |
| 795 | for plain-text sockets only, else :meth:`~socket.socket.send()` will be used) |
Victor Stinner | 3c3d3c7 | 2014-10-10 12:06:51 +0200 | [diff] [blame] | 796 | - :meth:`~socket.socket.shutdown()` |
Zachary Ware | ba9fb0d | 2014-06-11 15:02:25 -0500 | [diff] [blame] | 797 | |
Victor Stinner | 3c3d3c7 | 2014-10-10 12:06:51 +0200 | [diff] [blame] | 798 | However, since the SSL (and TLS) protocol has its own framing atop |
| 799 | of TCP, the SSL sockets abstraction can, in certain respects, diverge from |
| 800 | the specification of normal, OS-level sockets. See especially the |
| 801 | :ref:`notes on non-blocking sockets <ssl-nonblocking>`. |
Antoine Pitrou | e1f2f30 | 2010-09-19 13:56:11 +0000 | [diff] [blame] | 802 | |
Victor Stinner | d28fe8c | 2014-10-10 12:07:19 +0200 | [diff] [blame] | 803 | Usually, :class:`SSLSocket` are not created directly, but using the |
| 804 | :func:`wrap_socket` function or the :meth:`SSLContext.wrap_socket` method. |
| 805 | |
Victor Stinner | 92127a5 | 2014-10-10 12:43:17 +0200 | [diff] [blame] | 806 | .. versionchanged:: 3.5 |
| 807 | The :meth:`sendfile` method was added. |
| 808 | |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 809 | |
| 810 | SSL sockets also have the following additional methods and attributes: |
Antoine Pitrou | 792ff3e | 2010-09-19 13:19:21 +0000 | [diff] [blame] | 811 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 812 | .. method:: SSLSocket.read(len=0, buffer=None) |
| 813 | |
| 814 | Read up to *len* bytes of data from the SSL socket and return the result as |
| 815 | a ``bytes`` instance. If *buffer* is specified, then read into the buffer |
| 816 | instead, and return the number of bytes read. |
| 817 | |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 818 | Raise :exc:`SSLWantReadError` or :exc:`SSLWantWriteError` if the socket is |
Victor Stinner | cfb2a0a | 2014-10-10 12:45:10 +0200 | [diff] [blame] | 819 | :ref:`non-blocking <ssl-nonblocking>` and the read would block. |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 820 | |
| 821 | As at any time a re-negotiation is possible, a call to :meth:`read` can also |
| 822 | cause write operations. |
| 823 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 824 | .. method:: SSLSocket.write(buf) |
| 825 | |
| 826 | Write *buf* to the SSL socket and return the number of bytes written. The |
| 827 | *buf* argument must be an object supporting the buffer interface. |
| 828 | |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 829 | Raise :exc:`SSLWantReadError` or :exc:`SSLWantWriteError` if the socket is |
Victor Stinner | cfb2a0a | 2014-10-10 12:45:10 +0200 | [diff] [blame] | 830 | :ref:`non-blocking <ssl-nonblocking>` and the write would block. |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 831 | |
| 832 | As at any time a re-negotiation is possible, a call to :meth:`write` can |
| 833 | also cause read operations. |
| 834 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 835 | .. note:: |
| 836 | |
| 837 | The :meth:`~SSLSocket.read` and :meth:`~SSLSocket.write` methods are the |
| 838 | low-level methods that read and write unencrypted, application-level data |
| 839 | and and decrypt/encrypt it to encrypted, wire-level data. These methods |
| 840 | require an active SSL connection, i.e. the handshake was completed and |
| 841 | :meth:`SSLSocket.unwrap` was not called. |
| 842 | |
| 843 | Normally you should use the socket API methods like |
| 844 | :meth:`~socket.socket.recv` and :meth:`~socket.socket.send` instead of these |
| 845 | methods. |
| 846 | |
Bill Janssen | 48dc27c | 2007-12-05 03:38:10 +0000 | [diff] [blame] | 847 | .. method:: SSLSocket.do_handshake() |
| 848 | |
Antoine Pitrou | b3593ca | 2011-07-11 01:39:19 +0200 | [diff] [blame] | 849 | Perform the SSL setup handshake. |
Bill Janssen | 48dc27c | 2007-12-05 03:38:10 +0000 | [diff] [blame] | 850 | |
Christian Heimes | 1aa9a75 | 2013-12-02 02:41:19 +0100 | [diff] [blame] | 851 | .. versionchanged:: 3.4 |
Zachary Ware | 88a1977 | 2014-07-25 13:30:50 -0500 | [diff] [blame] | 852 | The handshake method also performs :func:`match_hostname` when the |
Christian Heimes | 1aa9a75 | 2013-12-02 02:41:19 +0100 | [diff] [blame] | 853 | :attr:`~SSLContext.check_hostname` attribute of the socket's |
| 854 | :attr:`~SSLSocket.context` is true. |
| 855 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 856 | .. method:: SSLSocket.getpeercert(binary_form=False) |
| 857 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 858 | If there is no certificate for the peer on the other end of the connection, |
Antoine Pitrou | 20b8555 | 2013-09-29 19:50:53 +0200 | [diff] [blame] | 859 | return ``None``. If the SSL handshake hasn't been done yet, raise |
| 860 | :exc:`ValueError`. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 861 | |
Antoine Pitrou | d34941a | 2013-04-16 20:27:17 +0200 | [diff] [blame] | 862 | If the ``binary_form`` parameter is :const:`False`, and a certificate was |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 863 | received from the peer, this method returns a :class:`dict` instance. If the |
| 864 | certificate was not validated, the dict is empty. If the certificate was |
Antoine Pitrou | b7c6c81 | 2012-08-16 22:14:43 +0200 | [diff] [blame] | 865 | validated, it returns a dict with several keys, amongst them ``subject`` |
| 866 | (the principal for which the certificate was issued) and ``issuer`` |
| 867 | (the principal issuing the certificate). If a certificate contains an |
| 868 | instance of the *Subject Alternative Name* extension (see :rfc:`3280`), |
| 869 | there will also be a ``subjectAltName`` key in the dictionary. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 870 | |
Antoine Pitrou | b7c6c81 | 2012-08-16 22:14:43 +0200 | [diff] [blame] | 871 | The ``subject`` and ``issuer`` fields are tuples containing the sequence |
| 872 | of relative distinguished names (RDNs) given in the certificate's data |
| 873 | structure for the respective fields, and each RDN is a sequence of |
| 874 | name-value pairs. Here is a real-world example:: |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 875 | |
Antoine Pitrou | b7c6c81 | 2012-08-16 22:14:43 +0200 | [diff] [blame] | 876 | {'issuer': ((('countryName', 'IL'),), |
| 877 | (('organizationName', 'StartCom Ltd.'),), |
| 878 | (('organizationalUnitName', |
| 879 | 'Secure Digital Certificate Signing'),), |
| 880 | (('commonName', |
| 881 | 'StartCom Class 2 Primary Intermediate Server CA'),)), |
| 882 | 'notAfter': 'Nov 22 08:15:19 2013 GMT', |
| 883 | 'notBefore': 'Nov 21 03:09:52 2011 GMT', |
| 884 | 'serialNumber': '95F0', |
| 885 | 'subject': ((('description', '571208-SLe257oHY9fVQ07Z'),), |
| 886 | (('countryName', 'US'),), |
| 887 | (('stateOrProvinceName', 'California'),), |
| 888 | (('localityName', 'San Francisco'),), |
| 889 | (('organizationName', 'Electronic Frontier Foundation, Inc.'),), |
| 890 | (('commonName', '*.eff.org'),), |
| 891 | (('emailAddress', 'hostmaster@eff.org'),)), |
| 892 | 'subjectAltName': (('DNS', '*.eff.org'), ('DNS', 'eff.org')), |
| 893 | 'version': 3} |
| 894 | |
| 895 | .. note:: |
Larry Hastings | 3732ed2 | 2014-03-15 21:13:56 -0700 | [diff] [blame] | 896 | |
Antoine Pitrou | b7c6c81 | 2012-08-16 22:14:43 +0200 | [diff] [blame] | 897 | To validate a certificate for a particular service, you can use the |
| 898 | :func:`match_hostname` function. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 899 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 900 | If the ``binary_form`` parameter is :const:`True`, and a certificate was |
| 901 | provided, this method returns the DER-encoded form of the entire certificate |
| 902 | as a sequence of bytes, or :const:`None` if the peer did not provide a |
Antoine Pitrou | d34941a | 2013-04-16 20:27:17 +0200 | [diff] [blame] | 903 | certificate. Whether the peer provides a certificate depends on the SSL |
| 904 | socket's role: |
| 905 | |
| 906 | * for a client SSL socket, the server will always provide a certificate, |
| 907 | regardless of whether validation was required; |
| 908 | |
| 909 | * for a server SSL socket, the client will only provide a certificate |
| 910 | when requested by the server; therefore :meth:`getpeercert` will return |
| 911 | :const:`None` if you used :const:`CERT_NONE` (rather than |
| 912 | :const:`CERT_OPTIONAL` or :const:`CERT_REQUIRED`). |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 913 | |
Antoine Pitrou | fb04691 | 2010-11-09 20:21:19 +0000 | [diff] [blame] | 914 | .. versionchanged:: 3.2 |
| 915 | The returned dictionary includes additional items such as ``issuer`` |
| 916 | and ``notBefore``. |
| 917 | |
Antoine Pitrou | 20b8555 | 2013-09-29 19:50:53 +0200 | [diff] [blame] | 918 | .. versionchanged:: 3.4 |
| 919 | :exc:`ValueError` is raised when the handshake isn't done. |
Christian Heimes | bd3a7f9 | 2013-11-21 03:40:15 +0100 | [diff] [blame] | 920 | The returned dictionary includes additional X509v3 extension items |
Larry Hastings | 3732ed2 | 2014-03-15 21:13:56 -0700 | [diff] [blame] | 921 | such as ``crlDistributionPoints``, ``caIssuers`` and ``OCSP`` URIs. |
Christian Heimes | bd3a7f9 | 2013-11-21 03:40:15 +0100 | [diff] [blame] | 922 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 923 | .. method:: SSLSocket.cipher() |
| 924 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 925 | Returns a three-value tuple containing the name of the cipher being used, the |
| 926 | version of the SSL protocol that defines its use, and the number of secret |
| 927 | bits being used. If no connection has been established, returns ``None``. |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 928 | |
Antoine Pitrou | 8abdb8a | 2011-12-20 10:13:40 +0100 | [diff] [blame] | 929 | .. method:: SSLSocket.compression() |
| 930 | |
| 931 | Return the compression algorithm being used as a string, or ``None`` |
| 932 | if the connection isn't compressed. |
| 933 | |
| 934 | If the higher-level protocol supports its own compression mechanism, |
| 935 | you can use :data:`OP_NO_COMPRESSION` to disable SSL-level compression. |
| 936 | |
| 937 | .. versionadded:: 3.3 |
| 938 | |
Antoine Pitrou | d649480 | 2011-07-21 01:11:30 +0200 | [diff] [blame] | 939 | .. method:: SSLSocket.get_channel_binding(cb_type="tls-unique") |
| 940 | |
| 941 | Get channel binding data for current connection, as a bytes object. Returns |
| 942 | ``None`` if not connected or the handshake has not been completed. |
| 943 | |
| 944 | The *cb_type* parameter allow selection of the desired channel binding |
| 945 | type. Valid channel binding types are listed in the |
| 946 | :data:`CHANNEL_BINDING_TYPES` list. Currently only the 'tls-unique' channel |
| 947 | binding, defined by :rfc:`5929`, is supported. :exc:`ValueError` will be |
| 948 | raised if an unsupported channel binding type is requested. |
| 949 | |
| 950 | .. versionadded:: 3.3 |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 951 | |
Antoine Pitrou | d5d17eb | 2012-03-22 00:23:03 +0100 | [diff] [blame] | 952 | .. method:: SSLSocket.selected_npn_protocol() |
| 953 | |
Antoine Pitrou | 47e4042 | 2014-09-04 21:00:10 +0200 | [diff] [blame] | 954 | Returns the higher-level protocol that was selected during the TLS/SSL |
| 955 | handshake. If :meth:`SSLContext.set_npn_protocols` was not called, or |
| 956 | if the other party does not support NPN, or if the handshake has not yet |
| 957 | happened, this will return ``None``. |
Antoine Pitrou | d5d17eb | 2012-03-22 00:23:03 +0100 | [diff] [blame] | 958 | |
| 959 | .. versionadded:: 3.3 |
| 960 | |
Benjamin Peterson | 4aeec04 | 2008-08-19 21:42:13 +0000 | [diff] [blame] | 961 | .. method:: SSLSocket.unwrap() |
| 962 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 963 | Performs the SSL shutdown handshake, which removes the TLS layer from the |
| 964 | underlying socket, and returns the underlying socket object. This can be |
| 965 | used to go from encrypted operation over a connection to unencrypted. The |
| 966 | returned socket should always be used for further communication with the |
| 967 | other side of the connection, rather than the original socket. |
Benjamin Peterson | 4aeec04 | 2008-08-19 21:42:13 +0000 | [diff] [blame] | 968 | |
Antoine Pitrou | 47e4042 | 2014-09-04 21:00:10 +0200 | [diff] [blame] | 969 | .. method:: SSLSocket.version() |
| 970 | |
| 971 | Return the actual SSL protocol version negotiated by the connection |
| 972 | as a string, or ``None`` is no secure connection is established. |
| 973 | As of this writing, possible return values include ``"SSLv2"``, |
| 974 | ``"SSLv3"``, ``"TLSv1"``, ``"TLSv1.1"`` and ``"TLSv1.2"``. |
| 975 | Recent OpenSSL versions may define more return values. |
| 976 | |
| 977 | .. versionadded:: 3.5 |
| 978 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 979 | .. method:: SSLSocket.pending() |
| 980 | |
| 981 | Returns the number of already decrypted bytes available for read, pending on |
| 982 | the connection. |
| 983 | |
Antoine Pitrou | ec883db | 2010-05-24 21:20:20 +0000 | [diff] [blame] | 984 | .. attribute:: SSLSocket.context |
| 985 | |
| 986 | The :class:`SSLContext` object this SSL socket is tied to. If the SSL |
| 987 | socket was created using the top-level :func:`wrap_socket` function |
| 988 | (rather than :meth:`SSLContext.wrap_socket`), this is a custom context |
| 989 | object created for this SSL socket. |
| 990 | |
| 991 | .. versionadded:: 3.2 |
| 992 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 993 | .. attribute:: SSLSocket.server_side |
| 994 | |
| 995 | A boolean which is ``True`` for server-side sockets and ``False`` for |
| 996 | client-side sockets. |
| 997 | |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 998 | .. versionadded:: 3.2 |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 999 | |
| 1000 | .. attribute:: SSLSocket.server_hostname |
| 1001 | |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 1002 | Hostname of the server: :class:`str` type, or ``None`` for server-side |
| 1003 | socket or if the hostname was not specified in the constructor. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1004 | |
Victor Stinner | 41f92c2 | 2014-10-10 12:05:56 +0200 | [diff] [blame] | 1005 | .. versionadded:: 3.2 |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1006 | |
Antoine Pitrou | ec883db | 2010-05-24 21:20:20 +0000 | [diff] [blame] | 1007 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1008 | SSL Contexts |
| 1009 | ------------ |
| 1010 | |
Antoine Pitrou | cafaad4 | 2010-05-24 15:58:43 +0000 | [diff] [blame] | 1011 | .. versionadded:: 3.2 |
| 1012 | |
Antoine Pitrou | b0182c8 | 2010-10-12 20:09:02 +0000 | [diff] [blame] | 1013 | An SSL context holds various data longer-lived than single SSL connections, |
| 1014 | such as SSL configuration options, certificate(s) and private key(s). |
| 1015 | It also manages a cache of SSL sessions for server-side sockets, in order |
| 1016 | to speed up repeated connections from the same clients. |
| 1017 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1018 | .. class:: SSLContext(protocol) |
| 1019 | |
Antoine Pitrou | b0182c8 | 2010-10-12 20:09:02 +0000 | [diff] [blame] | 1020 | Create a new SSL context. You must pass *protocol* which must be one |
| 1021 | of the ``PROTOCOL_*`` constants defined in this module. |
Antoine Pitrou | 5bef410 | 2013-11-23 16:16:29 +0100 | [diff] [blame] | 1022 | :data:`PROTOCOL_SSLv23` is currently recommended for maximum |
| 1023 | interoperability. |
| 1024 | |
| 1025 | .. seealso:: |
| 1026 | :func:`create_default_context` lets the :mod:`ssl` module choose |
| 1027 | security settings for a given purpose. |
Antoine Pitrou | b0182c8 | 2010-10-12 20:09:02 +0000 | [diff] [blame] | 1028 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1029 | |
| 1030 | :class:`SSLContext` objects have the following methods and attributes: |
| 1031 | |
Christian Heimes | 9a5395a | 2013-06-17 15:44:12 +0200 | [diff] [blame] | 1032 | .. method:: SSLContext.cert_store_stats() |
| 1033 | |
| 1034 | Get statistics about quantities of loaded X.509 certificates, count of |
| 1035 | X.509 certificates flagged as CA certificates and certificate revocation |
| 1036 | lists as dictionary. |
| 1037 | |
| 1038 | Example for a context with one CA cert and one other cert:: |
| 1039 | |
| 1040 | >>> context.cert_store_stats() |
| 1041 | {'crl': 0, 'x509_ca': 1, 'x509': 2} |
| 1042 | |
| 1043 | .. versionadded:: 3.4 |
| 1044 | |
Christian Heimes | efff706 | 2013-11-21 03:35:02 +0100 | [diff] [blame] | 1045 | |
Antoine Pitrou | 4fd1e6a | 2011-08-25 14:39:44 +0200 | [diff] [blame] | 1046 | .. method:: SSLContext.load_cert_chain(certfile, keyfile=None, password=None) |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1047 | |
| 1048 | Load a private key and the corresponding certificate. The *certfile* |
| 1049 | string must be the path to a single file in PEM format containing the |
| 1050 | certificate as well as any number of CA certificates needed to establish |
| 1051 | the certificate's authenticity. The *keyfile* string, if present, must |
| 1052 | point to a file containing the private key in. Otherwise the private |
| 1053 | key will be taken from *certfile* as well. See the discussion of |
| 1054 | :ref:`ssl-certificates` for more information on how the certificate |
| 1055 | is stored in the *certfile*. |
| 1056 | |
Antoine Pitrou | 4fd1e6a | 2011-08-25 14:39:44 +0200 | [diff] [blame] | 1057 | The *password* argument may be a function to call to get the password for |
| 1058 | decrypting the private key. It will only be called if the private key is |
| 1059 | encrypted and a password is necessary. It will be called with no arguments, |
| 1060 | and it should return a string, bytes, or bytearray. If the return value is |
| 1061 | a string it will be encoded as UTF-8 before using it to decrypt the key. |
| 1062 | Alternatively a string, bytes, or bytearray value may be supplied directly |
| 1063 | as the *password* argument. It will be ignored if the private key is not |
| 1064 | encrypted and no password is needed. |
| 1065 | |
| 1066 | If the *password* argument is not specified and a password is required, |
| 1067 | OpenSSL's built-in password prompting mechanism will be used to |
| 1068 | interactively prompt the user for a password. |
| 1069 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1070 | An :class:`SSLError` is raised if the private key doesn't |
| 1071 | match with the certificate. |
| 1072 | |
Antoine Pitrou | 4fd1e6a | 2011-08-25 14:39:44 +0200 | [diff] [blame] | 1073 | .. versionchanged:: 3.3 |
| 1074 | New optional argument *password*. |
| 1075 | |
Christian Heimes | 72d2850 | 2013-11-23 13:56:58 +0100 | [diff] [blame] | 1076 | .. method:: SSLContext.load_default_certs(purpose=Purpose.SERVER_AUTH) |
| 1077 | |
| 1078 | Load a set of default "certification authority" (CA) certificates from |
| 1079 | default locations. On Windows it loads CA certs from the ``CA`` and |
| 1080 | ``ROOT`` system stores. On other systems it calls |
| 1081 | :meth:`SSLContext.set_default_verify_paths`. In the future the method may |
| 1082 | load CA certificates from other locations, too. |
| 1083 | |
| 1084 | The *purpose* flag specifies what kind of CA certificates are loaded. The |
| 1085 | default settings :data:`Purpose.SERVER_AUTH` loads certificates, that are |
| 1086 | flagged and trusted for TLS web server authentication (client side |
Christian Heimes | 6b2ff98 | 2013-11-23 14:42:01 +0100 | [diff] [blame] | 1087 | sockets). :data:`Purpose.CLIENT_AUTH` loads CA certificates for client |
Christian Heimes | 72d2850 | 2013-11-23 13:56:58 +0100 | [diff] [blame] | 1088 | certificate verification on the server side. |
| 1089 | |
| 1090 | .. versionadded:: 3.4 |
| 1091 | |
Christian Heimes | efff706 | 2013-11-21 03:35:02 +0100 | [diff] [blame] | 1092 | .. method:: SSLContext.load_verify_locations(cafile=None, capath=None, cadata=None) |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1093 | |
| 1094 | Load a set of "certification authority" (CA) certificates used to validate |
| 1095 | other peers' certificates when :data:`verify_mode` is other than |
| 1096 | :data:`CERT_NONE`. At least one of *cafile* or *capath* must be specified. |
| 1097 | |
Christian Heimes | 2258779 | 2013-11-21 23:56:13 +0100 | [diff] [blame] | 1098 | This method can also load certification revocation lists (CRLs) in PEM or |
Donald Stufft | 8b852f1 | 2014-05-20 12:58:38 -0400 | [diff] [blame] | 1099 | DER format. In order to make use of CRLs, :attr:`SSLContext.verify_flags` |
Christian Heimes | 2258779 | 2013-11-21 23:56:13 +0100 | [diff] [blame] | 1100 | must be configured properly. |
| 1101 | |
Christian Heimes | 3e738f9 | 2013-06-09 18:07:16 +0200 | [diff] [blame] | 1102 | The *cafile* string, if present, is the path to a file of concatenated |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1103 | CA certificates in PEM format. See the discussion of |
| 1104 | :ref:`ssl-certificates` for more information about how to arrange the |
| 1105 | certificates in this file. |
| 1106 | |
| 1107 | The *capath* string, if present, is |
| 1108 | the path to a directory containing several CA certificates in PEM format, |
| 1109 | following an `OpenSSL specific layout |
| 1110 | <http://www.openssl.org/docs/ssl/SSL_CTX_load_verify_locations.html>`_. |
| 1111 | |
Christian Heimes | efff706 | 2013-11-21 03:35:02 +0100 | [diff] [blame] | 1112 | The *cadata* object, if present, is either an ASCII string of one or more |
| 1113 | PEM-encoded certificates or a bytes-like object of DER-encoded |
| 1114 | certificates. Like with *capath* extra lines around PEM-encoded |
| 1115 | certificates are ignored but at least one certificate must be present. |
| 1116 | |
| 1117 | .. versionchanged:: 3.4 |
| 1118 | New optional argument *cadata* |
| 1119 | |
Christian Heimes | 9a5395a | 2013-06-17 15:44:12 +0200 | [diff] [blame] | 1120 | .. method:: SSLContext.get_ca_certs(binary_form=False) |
| 1121 | |
| 1122 | Get a list of loaded "certification authority" (CA) certificates. If the |
| 1123 | ``binary_form`` parameter is :const:`False` each list |
| 1124 | entry is a dict like the output of :meth:`SSLSocket.getpeercert`. Otherwise |
| 1125 | the method returns a list of DER-encoded certificates. The returned list |
| 1126 | does not contain certificates from *capath* unless a certificate was |
| 1127 | requested and loaded by a SSL connection. |
| 1128 | |
Larry Hastings | d36fc43 | 2013-08-03 02:49:53 -0700 | [diff] [blame] | 1129 | .. versionadded:: 3.4 |
Christian Heimes | 9a5395a | 2013-06-17 15:44:12 +0200 | [diff] [blame] | 1130 | |
Antoine Pitrou | 664c2d1 | 2010-11-17 20:29:42 +0000 | [diff] [blame] | 1131 | .. method:: SSLContext.set_default_verify_paths() |
| 1132 | |
| 1133 | Load a set of default "certification authority" (CA) certificates from |
| 1134 | a filesystem path defined when building the OpenSSL library. Unfortunately, |
| 1135 | there's no easy way to know whether this method succeeds: no error is |
| 1136 | returned if no certificates are to be found. When the OpenSSL library is |
| 1137 | provided as part of the operating system, though, it is likely to be |
| 1138 | configured properly. |
| 1139 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1140 | .. method:: SSLContext.set_ciphers(ciphers) |
| 1141 | |
| 1142 | Set the available ciphers for sockets created with this context. |
| 1143 | It should be a string in the `OpenSSL cipher list format |
| 1144 | <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`_. |
| 1145 | If no cipher can be selected (because compile-time options or other |
| 1146 | configuration forbids use of all the specified ciphers), an |
| 1147 | :class:`SSLError` will be raised. |
| 1148 | |
| 1149 | .. note:: |
| 1150 | when connected, the :meth:`SSLSocket.cipher` method of SSL sockets will |
| 1151 | give the currently selected cipher. |
| 1152 | |
Antoine Pitrou | d5d17eb | 2012-03-22 00:23:03 +0100 | [diff] [blame] | 1153 | .. method:: SSLContext.set_npn_protocols(protocols) |
| 1154 | |
R David Murray | c7f7579 | 2013-06-26 15:11:12 -0400 | [diff] [blame] | 1155 | Specify which protocols the socket should advertise during the SSL/TLS |
Antoine Pitrou | d5d17eb | 2012-03-22 00:23:03 +0100 | [diff] [blame] | 1156 | handshake. It should be a list of strings, like ``['http/1.1', 'spdy/2']``, |
| 1157 | ordered by preference. The selection of a protocol will happen during the |
| 1158 | handshake, and will play out according to the `NPN draft specification |
| 1159 | <http://tools.ietf.org/html/draft-agl-tls-nextprotoneg>`_. After a |
| 1160 | successful handshake, the :meth:`SSLSocket.selected_npn_protocol` method will |
| 1161 | return the agreed-upon protocol. |
| 1162 | |
| 1163 | This method will raise :exc:`NotImplementedError` if :data:`HAS_NPN` is |
| 1164 | False. |
| 1165 | |
| 1166 | .. versionadded:: 3.3 |
| 1167 | |
Antoine Pitrou | 58ddc9d | 2013-01-05 21:20:29 +0100 | [diff] [blame] | 1168 | .. method:: SSLContext.set_servername_callback(server_name_callback) |
| 1169 | |
| 1170 | Register a callback function that will be called after the TLS Client Hello |
| 1171 | handshake message has been received by the SSL/TLS server when the TLS client |
| 1172 | specifies a server name indication. The server name indication mechanism |
| 1173 | is specified in :rfc:`6066` section 3 - Server Name Indication. |
| 1174 | |
| 1175 | Only one callback can be set per ``SSLContext``. If *server_name_callback* |
| 1176 | is ``None`` then the callback is disabled. Calling this function a |
| 1177 | subsequent time will disable the previously registered callback. |
| 1178 | |
| 1179 | The callback function, *server_name_callback*, will be called with three |
| 1180 | arguments; the first being the :class:`ssl.SSLSocket`, the second is a string |
| 1181 | that represents the server name that the client is intending to communicate |
Antoine Pitrou | 50b24d0 | 2013-04-11 20:48:42 +0200 | [diff] [blame] | 1182 | (or :const:`None` if the TLS Client Hello does not contain a server name) |
Antoine Pitrou | 58ddc9d | 2013-01-05 21:20:29 +0100 | [diff] [blame] | 1183 | and the third argument is the original :class:`SSLContext`. The server name |
| 1184 | argument is the IDNA decoded server name. |
| 1185 | |
| 1186 | A typical use of this callback is to change the :class:`ssl.SSLSocket`'s |
| 1187 | :attr:`SSLSocket.context` attribute to a new object of type |
| 1188 | :class:`SSLContext` representing a certificate chain that matches the server |
| 1189 | name. |
| 1190 | |
| 1191 | Due to the early negotiation phase of the TLS connection, only limited |
| 1192 | methods and attributes are usable like |
| 1193 | :meth:`SSLSocket.selected_npn_protocol` and :attr:`SSLSocket.context`. |
| 1194 | :meth:`SSLSocket.getpeercert`, :meth:`SSLSocket.getpeercert`, |
| 1195 | :meth:`SSLSocket.cipher` and :meth:`SSLSocket.compress` methods require that |
| 1196 | the TLS connection has progressed beyond the TLS Client Hello and therefore |
| 1197 | will not contain return meaningful values nor can they be called safely. |
| 1198 | |
| 1199 | The *server_name_callback* function must return ``None`` to allow the |
Terry Jan Reedy | 8e7586b | 2013-03-11 18:38:13 -0400 | [diff] [blame] | 1200 | TLS negotiation to continue. If a TLS failure is required, a constant |
Antoine Pitrou | 58ddc9d | 2013-01-05 21:20:29 +0100 | [diff] [blame] | 1201 | :const:`ALERT_DESCRIPTION_* <ALERT_DESCRIPTION_INTERNAL_ERROR>` can be |
| 1202 | returned. Other return values will result in a TLS fatal error with |
| 1203 | :const:`ALERT_DESCRIPTION_INTERNAL_ERROR`. |
| 1204 | |
Zachary Ware | 88a1977 | 2014-07-25 13:30:50 -0500 | [diff] [blame] | 1205 | If there is an IDNA decoding error on the server name, the TLS connection |
Antoine Pitrou | 58ddc9d | 2013-01-05 21:20:29 +0100 | [diff] [blame] | 1206 | will terminate with an :const:`ALERT_DESCRIPTION_INTERNAL_ERROR` fatal TLS |
| 1207 | alert message to the client. |
| 1208 | |
| 1209 | If an exception is raised from the *server_name_callback* function the TLS |
| 1210 | connection will terminate with a fatal TLS alert message |
| 1211 | :const:`ALERT_DESCRIPTION_HANDSHAKE_FAILURE`. |
| 1212 | |
| 1213 | This method will raise :exc:`NotImplementedError` if the OpenSSL library |
| 1214 | had OPENSSL_NO_TLSEXT defined when it was built. |
| 1215 | |
| 1216 | .. versionadded:: 3.4 |
| 1217 | |
Antoine Pitrou | 0e576f1 | 2011-12-22 10:03:38 +0100 | [diff] [blame] | 1218 | .. method:: SSLContext.load_dh_params(dhfile) |
| 1219 | |
| 1220 | Load the key generation parameters for Diffie-Helman (DH) key exchange. |
| 1221 | Using DH key exchange improves forward secrecy at the expense of |
| 1222 | computational resources (both on the server and on the client). |
| 1223 | The *dhfile* parameter should be the path to a file containing DH |
| 1224 | parameters in PEM format. |
| 1225 | |
| 1226 | This setting doesn't apply to client sockets. You can also use the |
| 1227 | :data:`OP_SINGLE_DH_USE` option to further improve security. |
| 1228 | |
| 1229 | .. versionadded:: 3.3 |
| 1230 | |
Antoine Pitrou | 923df6f | 2011-12-19 17:16:51 +0100 | [diff] [blame] | 1231 | .. method:: SSLContext.set_ecdh_curve(curve_name) |
| 1232 | |
Antoine Pitrou | 0e576f1 | 2011-12-22 10:03:38 +0100 | [diff] [blame] | 1233 | Set the curve name for Elliptic Curve-based Diffie-Hellman (ECDH) key |
| 1234 | exchange. ECDH is significantly faster than regular DH while arguably |
| 1235 | as secure. The *curve_name* parameter should be a string describing |
Antoine Pitrou | 923df6f | 2011-12-19 17:16:51 +0100 | [diff] [blame] | 1236 | a well-known elliptic curve, for example ``prime256v1`` for a widely |
| 1237 | supported curve. |
| 1238 | |
| 1239 | This setting doesn't apply to client sockets. You can also use the |
| 1240 | :data:`OP_SINGLE_ECDH_USE` option to further improve security. |
| 1241 | |
Antoine Pitrou | 501da61 | 2011-12-21 09:27:41 +0100 | [diff] [blame] | 1242 | This method is not available if :data:`HAS_ECDH` is False. |
| 1243 | |
Antoine Pitrou | 923df6f | 2011-12-19 17:16:51 +0100 | [diff] [blame] | 1244 | .. versionadded:: 3.3 |
| 1245 | |
| 1246 | .. seealso:: |
| 1247 | `SSL/TLS & Perfect Forward Secrecy <http://vincent.bernat.im/en/blog/2011-ssl-perfect-forward-secrecy.html>`_ |
| 1248 | Vincent Bernat. |
| 1249 | |
Antoine Pitrou | d532321 | 2010-10-22 18:19:07 +0000 | [diff] [blame] | 1250 | .. method:: SSLContext.wrap_socket(sock, server_side=False, \ |
| 1251 | do_handshake_on_connect=True, suppress_ragged_eofs=True, \ |
| 1252 | server_hostname=None) |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1253 | |
| 1254 | Wrap an existing Python socket *sock* and return an :class:`SSLSocket` |
Antoine Pitrou | 3e86ba4 | 2013-12-28 17:26:33 +0100 | [diff] [blame] | 1255 | object. *sock* must be a :data:`~socket.SOCK_STREAM` socket; other socket |
| 1256 | types are unsupported. |
| 1257 | |
| 1258 | The returned SSL socket is tied to the context, its settings and |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1259 | certificates. The parameters *server_side*, *do_handshake_on_connect* |
| 1260 | and *suppress_ragged_eofs* have the same meaning as in the top-level |
| 1261 | :func:`wrap_socket` function. |
| 1262 | |
Antoine Pitrou | d532321 | 2010-10-22 18:19:07 +0000 | [diff] [blame] | 1263 | On client connections, the optional parameter *server_hostname* specifies |
| 1264 | the hostname of the service which we are connecting to. This allows a |
| 1265 | single server to host multiple SSL-based services with distinct certificates, |
| 1266 | quite similarly to HTTP virtual hosts. Specifying *server_hostname* |
| 1267 | will raise a :exc:`ValueError` if the OpenSSL library doesn't have support |
| 1268 | for it (that is, if :data:`HAS_SNI` is :const:`False`). Specifying |
| 1269 | *server_hostname* will also raise a :exc:`ValueError` if *server_side* |
| 1270 | is true. |
| 1271 | |
Victor Stinner | 805b262 | 2014-10-10 12:49:08 +0200 | [diff] [blame] | 1272 | .. method:: SSLContext.wrap_bio(incoming, outgoing, server_side=False, \ |
| 1273 | server_hostname=None) |
| 1274 | |
| 1275 | Create a new :class:`SSLObject` instance by wrapping the BIO objects |
| 1276 | *incoming* and *outgoing*. The SSL routines will read input data from the |
| 1277 | incoming BIO and write data to the outgoing BIO. |
| 1278 | |
| 1279 | The *server_side* and *server_hostname* parameters have the same meaning as |
| 1280 | in :meth:`SSLContext.wrap_socket`. |
| 1281 | |
Antoine Pitrou | b0182c8 | 2010-10-12 20:09:02 +0000 | [diff] [blame] | 1282 | .. method:: SSLContext.session_stats() |
| 1283 | |
| 1284 | Get statistics about the SSL sessions created or managed by this context. |
| 1285 | A dictionary is returned which maps the names of each `piece of information |
| 1286 | <http://www.openssl.org/docs/ssl/SSL_CTX_sess_number.html>`_ to their |
| 1287 | numeric values. For example, here is the total number of hits and misses |
| 1288 | in the session cache since the context was created:: |
| 1289 | |
| 1290 | >>> stats = context.session_stats() |
| 1291 | >>> stats['hits'], stats['misses'] |
| 1292 | (0, 0) |
| 1293 | |
Christian Heimes | f22e8e5 | 2013-11-22 02:22:51 +0100 | [diff] [blame] | 1294 | .. method:: SSLContext.get_ca_certs(binary_form=False) |
| 1295 | |
| 1296 | Returns a list of dicts with information of loaded CA certs. If the |
Serhiy Storchaka | 0e90e99 | 2013-11-29 12:19:53 +0200 | [diff] [blame] | 1297 | optional argument is true, returns a DER-encoded copy of the CA |
Christian Heimes | f22e8e5 | 2013-11-22 02:22:51 +0100 | [diff] [blame] | 1298 | certificate. |
| 1299 | |
| 1300 | .. note:: |
| 1301 | Certificates in a capath directory aren't loaded unless they have |
| 1302 | been used at least once. |
| 1303 | |
| 1304 | .. versionadded:: 3.4 |
| 1305 | |
Christian Heimes | 1aa9a75 | 2013-12-02 02:41:19 +0100 | [diff] [blame] | 1306 | .. attribute:: SSLContext.check_hostname |
| 1307 | |
| 1308 | Wether to match the peer cert's hostname with :func:`match_hostname` in |
| 1309 | :meth:`SSLSocket.do_handshake`. The context's |
| 1310 | :attr:`~SSLContext.verify_mode` must be set to :data:`CERT_OPTIONAL` or |
| 1311 | :data:`CERT_REQUIRED`, and you must pass *server_hostname* to |
| 1312 | :meth:`~SSLContext.wrap_socket` in order to match the hostname. |
| 1313 | |
| 1314 | Example:: |
| 1315 | |
| 1316 | import socket, ssl |
| 1317 | |
| 1318 | context = ssl.SSLContext(ssl.PROTOCOL_TLSv1) |
| 1319 | context.verify_mode = ssl.CERT_REQUIRED |
| 1320 | context.check_hostname = True |
| 1321 | context.load_default_certs() |
| 1322 | |
| 1323 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
Berker Peksag | 38bf87c | 2014-07-17 05:00:36 +0300 | [diff] [blame] | 1324 | ssl_sock = context.wrap_socket(s, server_hostname='www.verisign.com') |
| 1325 | ssl_sock.connect(('www.verisign.com', 443)) |
Christian Heimes | 1aa9a75 | 2013-12-02 02:41:19 +0100 | [diff] [blame] | 1326 | |
| 1327 | .. versionadded:: 3.4 |
| 1328 | |
| 1329 | .. note:: |
| 1330 | |
| 1331 | This features requires OpenSSL 0.9.8f or newer. |
| 1332 | |
Antoine Pitrou | b521877 | 2010-05-21 09:56:06 +0000 | [diff] [blame] | 1333 | .. attribute:: SSLContext.options |
| 1334 | |
| 1335 | An integer representing the set of SSL options enabled on this context. |
| 1336 | The default value is :data:`OP_ALL`, but you can specify other options |
| 1337 | such as :data:`OP_NO_SSLv2` by ORing them together. |
| 1338 | |
| 1339 | .. note:: |
| 1340 | With versions of OpenSSL older than 0.9.8m, it is only possible |
| 1341 | to set options, not to clear them. Attempting to clear an option |
| 1342 | (by resetting the corresponding bits) will raise a ``ValueError``. |
| 1343 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1344 | .. attribute:: SSLContext.protocol |
| 1345 | |
| 1346 | The protocol version chosen when constructing the context. This attribute |
| 1347 | is read-only. |
| 1348 | |
Christian Heimes | 2258779 | 2013-11-21 23:56:13 +0100 | [diff] [blame] | 1349 | .. attribute:: SSLContext.verify_flags |
| 1350 | |
| 1351 | The flags for certificate verification operations. You can set flags like |
| 1352 | :data:`VERIFY_CRL_CHECK_LEAF` by ORing them together. By default OpenSSL |
| 1353 | does neither require nor verify certificate revocation lists (CRLs). |
Christian Heimes | 2427b50 | 2013-11-23 11:24:32 +0100 | [diff] [blame] | 1354 | Available only with openssl version 0.9.8+. |
Christian Heimes | 2258779 | 2013-11-21 23:56:13 +0100 | [diff] [blame] | 1355 | |
| 1356 | .. versionadded:: 3.4 |
| 1357 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1358 | .. attribute:: SSLContext.verify_mode |
| 1359 | |
| 1360 | Whether to try to verify other peers' certificates and how to behave |
| 1361 | if verification fails. This attribute must be one of |
| 1362 | :data:`CERT_NONE`, :data:`CERT_OPTIONAL` or :data:`CERT_REQUIRED`. |
| 1363 | |
| 1364 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1365 | .. index:: single: certificates |
| 1366 | |
| 1367 | .. index:: single: X509 certificate |
| 1368 | |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1369 | .. _ssl-certificates: |
| 1370 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1371 | Certificates |
| 1372 | ------------ |
| 1373 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1374 | Certificates in general are part of a public-key / private-key system. In this |
| 1375 | system, each *principal*, (which may be a machine, or a person, or an |
| 1376 | organization) is assigned a unique two-part encryption key. One part of the key |
| 1377 | is public, and is called the *public key*; the other part is kept secret, and is |
| 1378 | called the *private key*. The two parts are related, in that if you encrypt a |
| 1379 | message with one of the parts, you can decrypt it with the other part, and |
| 1380 | **only** with the other part. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1381 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1382 | A certificate contains information about two principals. It contains the name |
| 1383 | of a *subject*, and the subject's public key. It also contains a statement by a |
| 1384 | second principal, the *issuer*, that the subject is who he claims to be, and |
| 1385 | that this is indeed the subject's public key. The issuer's statement is signed |
| 1386 | with the issuer's private key, which only the issuer knows. However, anyone can |
| 1387 | verify the issuer's statement by finding the issuer's public key, decrypting the |
| 1388 | statement with it, and comparing it to the other information in the certificate. |
| 1389 | The certificate also contains information about the time period over which it is |
| 1390 | valid. This is expressed as two fields, called "notBefore" and "notAfter". |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1391 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1392 | In the Python use of certificates, a client or server can use a certificate to |
| 1393 | prove who they are. The other side of a network connection can also be required |
| 1394 | to produce a certificate, and that certificate can be validated to the |
| 1395 | satisfaction of the client or server that requires such validation. The |
| 1396 | connection attempt can be set to raise an exception if the validation fails. |
| 1397 | Validation is done automatically, by the underlying OpenSSL framework; the |
| 1398 | application need not concern itself with its mechanics. But the application |
| 1399 | does usually need to provide sets of certificates to allow this process to take |
| 1400 | place. |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1401 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1402 | Python uses files to contain certificates. They should be formatted as "PEM" |
| 1403 | (see :rfc:`1422`), which is a base-64 encoded form wrapped with a header line |
| 1404 | and a footer line:: |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1405 | |
| 1406 | -----BEGIN CERTIFICATE----- |
| 1407 | ... (certificate in base64 PEM encoding) ... |
| 1408 | -----END CERTIFICATE----- |
| 1409 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1410 | Certificate chains |
| 1411 | ^^^^^^^^^^^^^^^^^^ |
| 1412 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1413 | The Python files which contain certificates can contain a sequence of |
| 1414 | certificates, sometimes called a *certificate chain*. This chain should start |
| 1415 | with the specific certificate for the principal who "is" the client or server, |
| 1416 | and then the certificate for the issuer of that certificate, and then the |
| 1417 | certificate for the issuer of *that* certificate, and so on up the chain till |
| 1418 | you get to a certificate which is *self-signed*, that is, a certificate which |
| 1419 | has the same subject and issuer, sometimes called a *root certificate*. The |
| 1420 | certificates should just be concatenated together in the certificate file. For |
| 1421 | example, suppose we had a three certificate chain, from our server certificate |
| 1422 | to the certificate of the certification authority that signed our server |
| 1423 | certificate, to the root certificate of the agency which issued the |
| 1424 | certification authority's certificate:: |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1425 | |
| 1426 | -----BEGIN CERTIFICATE----- |
| 1427 | ... (certificate for your server)... |
| 1428 | -----END CERTIFICATE----- |
| 1429 | -----BEGIN CERTIFICATE----- |
| 1430 | ... (the certificate for the CA)... |
| 1431 | -----END CERTIFICATE----- |
| 1432 | -----BEGIN CERTIFICATE----- |
| 1433 | ... (the root certificate for the CA's issuer)... |
| 1434 | -----END CERTIFICATE----- |
| 1435 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1436 | CA certificates |
| 1437 | ^^^^^^^^^^^^^^^ |
| 1438 | |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1439 | If you are going to require validation of the other side of the connection's |
| 1440 | certificate, you need to provide a "CA certs" file, filled with the certificate |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1441 | chains for each issuer you are willing to trust. Again, this file just contains |
| 1442 | these chains concatenated together. For validation, Python will use the first |
Donald Stufft | 4137465 | 2014-03-24 19:26:03 -0400 | [diff] [blame] | 1443 | chain it finds in the file which matches. The platform's certificates file can |
| 1444 | be used by calling :meth:`SSLContext.load_default_certs`, this is done |
| 1445 | automatically with :func:`.create_default_context`. |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1446 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1447 | Combined key and certificate |
| 1448 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1449 | |
| 1450 | Often the private key is stored in the same file as the certificate; in this |
| 1451 | case, only the ``certfile`` parameter to :meth:`SSLContext.load_cert_chain` |
| 1452 | and :func:`wrap_socket` needs to be passed. If the private key is stored |
| 1453 | with the certificate, it should come before the first certificate in |
| 1454 | the certificate chain:: |
| 1455 | |
| 1456 | -----BEGIN RSA PRIVATE KEY----- |
| 1457 | ... (private key in base64 encoding) ... |
| 1458 | -----END RSA PRIVATE KEY----- |
| 1459 | -----BEGIN CERTIFICATE----- |
| 1460 | ... (certificate in base64 PEM encoding) ... |
| 1461 | -----END CERTIFICATE----- |
| 1462 | |
| 1463 | Self-signed certificates |
| 1464 | ^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1465 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1466 | If you are going to create a server that provides SSL-encrypted connection |
| 1467 | services, you will need to acquire a certificate for that service. There are |
| 1468 | many ways of acquiring appropriate certificates, such as buying one from a |
| 1469 | certification authority. Another common practice is to generate a self-signed |
| 1470 | certificate. The simplest way to do this is with the OpenSSL package, using |
| 1471 | something like the following:: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1472 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1473 | % openssl req -new -x509 -days 365 -nodes -out cert.pem -keyout cert.pem |
| 1474 | Generating a 1024 bit RSA private key |
| 1475 | .......++++++ |
| 1476 | .............................++++++ |
| 1477 | writing new private key to 'cert.pem' |
| 1478 | ----- |
| 1479 | You are about to be asked to enter information that will be incorporated |
| 1480 | into your certificate request. |
| 1481 | What you are about to enter is what is called a Distinguished Name or a DN. |
| 1482 | There are quite a few fields but you can leave some blank |
| 1483 | For some fields there will be a default value, |
| 1484 | If you enter '.', the field will be left blank. |
| 1485 | ----- |
| 1486 | Country Name (2 letter code) [AU]:US |
| 1487 | State or Province Name (full name) [Some-State]:MyState |
| 1488 | Locality Name (eg, city) []:Some City |
| 1489 | Organization Name (eg, company) [Internet Widgits Pty Ltd]:My Organization, Inc. |
| 1490 | Organizational Unit Name (eg, section) []:My Group |
| 1491 | Common Name (eg, YOUR name) []:myserver.mygroup.myorganization.com |
| 1492 | Email Address []:ops@myserver.mygroup.myorganization.com |
| 1493 | % |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1494 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1495 | The disadvantage of a self-signed certificate is that it is its own root |
| 1496 | certificate, and no one else will have it in their cache of known (and trusted) |
| 1497 | root certificates. |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1498 | |
| 1499 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1500 | Examples |
| 1501 | -------- |
| 1502 | |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1503 | Testing for SSL support |
| 1504 | ^^^^^^^^^^^^^^^^^^^^^^^ |
| 1505 | |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1506 | To test for the presence of SSL support in a Python installation, user code |
| 1507 | should use the following idiom:: |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1508 | |
| 1509 | try: |
Georg Brandl | 8a7e5da | 2011-01-02 19:07:51 +0000 | [diff] [blame] | 1510 | import ssl |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1511 | except ImportError: |
Georg Brandl | 8a7e5da | 2011-01-02 19:07:51 +0000 | [diff] [blame] | 1512 | pass |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1513 | else: |
Georg Brandl | 8a7e5da | 2011-01-02 19:07:51 +0000 | [diff] [blame] | 1514 | ... # do something that requires SSL support |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1515 | |
| 1516 | Client-side operation |
| 1517 | ^^^^^^^^^^^^^^^^^^^^^ |
| 1518 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1519 | This example connects to an SSL server and prints the server's certificate:: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1520 | |
| 1521 | import socket, ssl, pprint |
| 1522 | |
| 1523 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1524 | # require a certificate from the server |
| 1525 | ssl_sock = ssl.wrap_socket(s, |
| 1526 | ca_certs="/etc/ca_certs_file", |
| 1527 | cert_reqs=ssl.CERT_REQUIRED) |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1528 | ssl_sock.connect(('www.verisign.com', 443)) |
| 1529 | |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1530 | pprint.pprint(ssl_sock.getpeercert()) |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1531 | # note that closing the SSLSocket will also close the underlying socket |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1532 | ssl_sock.close() |
| 1533 | |
Antoine Pitrou | 441ae04 | 2012-01-06 20:06:15 +0100 | [diff] [blame] | 1534 | As of January 6, 2012, the certificate printed by this program looks like |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1535 | this:: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1536 | |
Antoine Pitrou | 441ae04 | 2012-01-06 20:06:15 +0100 | [diff] [blame] | 1537 | {'issuer': ((('countryName', 'US'),), |
| 1538 | (('organizationName', 'VeriSign, Inc.'),), |
| 1539 | (('organizationalUnitName', 'VeriSign Trust Network'),), |
| 1540 | (('organizationalUnitName', |
| 1541 | 'Terms of use at https://www.verisign.com/rpa (c)06'),), |
| 1542 | (('commonName', |
| 1543 | 'VeriSign Class 3 Extended Validation SSL SGC CA'),)), |
| 1544 | 'notAfter': 'May 25 23:59:59 2012 GMT', |
| 1545 | 'notBefore': 'May 26 00:00:00 2010 GMT', |
| 1546 | 'serialNumber': '53D2BEF924A7245E83CA01E46CAA2477', |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1547 | 'subject': ((('1.3.6.1.4.1.311.60.2.1.3', 'US'),), |
| 1548 | (('1.3.6.1.4.1.311.60.2.1.2', 'Delaware'),), |
| 1549 | (('businessCategory', 'V1.0, Clause 5.(b)'),), |
| 1550 | (('serialNumber', '2497886'),), |
| 1551 | (('countryName', 'US'),), |
| 1552 | (('postalCode', '94043'),), |
| 1553 | (('stateOrProvinceName', 'California'),), |
| 1554 | (('localityName', 'Mountain View'),), |
| 1555 | (('streetAddress', '487 East Middlefield Road'),), |
| 1556 | (('organizationName', 'VeriSign, Inc.'),), |
| 1557 | (('organizationalUnitName', ' Production Security Services'),), |
Antoine Pitrou | 441ae04 | 2012-01-06 20:06:15 +0100 | [diff] [blame] | 1558 | (('commonName', 'www.verisign.com'),)), |
| 1559 | 'subjectAltName': (('DNS', 'www.verisign.com'), |
| 1560 | ('DNS', 'verisign.com'), |
| 1561 | ('DNS', 'www.verisign.net'), |
| 1562 | ('DNS', 'verisign.net'), |
| 1563 | ('DNS', 'www.verisign.mobi'), |
| 1564 | ('DNS', 'verisign.mobi'), |
| 1565 | ('DNS', 'www.verisign.eu'), |
| 1566 | ('DNS', 'verisign.eu')), |
| 1567 | 'version': 3} |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1568 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1569 | This other example first creates an SSL context, instructs it to verify |
| 1570 | certificates sent by peers, and feeds it a set of recognized certificate |
| 1571 | authorities (CA):: |
| 1572 | |
| 1573 | >>> context = ssl.SSLContext(ssl.PROTOCOL_SSLv23) |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1574 | >>> context.verify_mode = ssl.CERT_REQUIRED |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1575 | >>> context.load_verify_locations("/etc/ssl/certs/ca-bundle.crt") |
| 1576 | |
| 1577 | (it is assumed your operating system places a bundle of all CA certificates |
| 1578 | in ``/etc/ssl/certs/ca-bundle.crt``; if not, you'll get an error and have |
| 1579 | to adjust the location) |
| 1580 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1581 | When you use the context to connect to a server, :const:`CERT_REQUIRED` |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1582 | validates the server certificate: it ensures that the server certificate |
| 1583 | was signed with one of the CA certificates, and checks the signature for |
| 1584 | correctness:: |
| 1585 | |
| 1586 | >>> conn = context.wrap_socket(socket.socket(socket.AF_INET)) |
| 1587 | >>> conn.connect(("linuxfr.org", 443)) |
| 1588 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1589 | You should then fetch the certificate and check its fields for conformity:: |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1590 | |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1591 | >>> cert = conn.getpeercert() |
| 1592 | >>> ssl.match_hostname(cert, "linuxfr.org") |
| 1593 | |
| 1594 | Visual inspection shows that the certificate does identify the desired service |
| 1595 | (that is, the HTTPS host ``linuxfr.org``):: |
| 1596 | |
| 1597 | >>> pprint.pprint(cert) |
Antoine Pitrou | 441ae04 | 2012-01-06 20:06:15 +0100 | [diff] [blame] | 1598 | {'issuer': ((('organizationName', 'CAcert Inc.'),), |
| 1599 | (('organizationalUnitName', 'http://www.CAcert.org'),), |
| 1600 | (('commonName', 'CAcert Class 3 Root'),)), |
| 1601 | 'notAfter': 'Jun 7 21:02:24 2013 GMT', |
| 1602 | 'notBefore': 'Jun 8 21:02:24 2011 GMT', |
| 1603 | 'serialNumber': 'D3E9', |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1604 | 'subject': ((('commonName', 'linuxfr.org'),),), |
Antoine Pitrou | 441ae04 | 2012-01-06 20:06:15 +0100 | [diff] [blame] | 1605 | 'subjectAltName': (('DNS', 'linuxfr.org'), |
| 1606 | ('othername', '<unsupported>'), |
| 1607 | ('DNS', 'linuxfr.org'), |
| 1608 | ('othername', '<unsupported>'), |
| 1609 | ('DNS', 'dev.linuxfr.org'), |
| 1610 | ('othername', '<unsupported>'), |
| 1611 | ('DNS', 'prod.linuxfr.org'), |
| 1612 | ('othername', '<unsupported>'), |
| 1613 | ('DNS', 'alpha.linuxfr.org'), |
| 1614 | ('othername', '<unsupported>'), |
| 1615 | ('DNS', '*.linuxfr.org'), |
| 1616 | ('othername', '<unsupported>')), |
| 1617 | 'version': 3} |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1618 | |
| 1619 | Now that you are assured of its authenticity, you can proceed to talk with |
| 1620 | the server:: |
| 1621 | |
Antoine Pitrou | dab6426 | 2010-09-19 13:31:06 +0000 | [diff] [blame] | 1622 | >>> conn.sendall(b"HEAD / HTTP/1.0\r\nHost: linuxfr.org\r\n\r\n") |
| 1623 | >>> pprint.pprint(conn.recv(1024).split(b"\r\n")) |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1624 | [b'HTTP/1.1 302 Found', |
| 1625 | b'Date: Sun, 16 May 2010 13:43:28 GMT', |
| 1626 | b'Server: Apache/2.2', |
| 1627 | b'Location: https://linuxfr.org/pub/', |
| 1628 | b'Vary: Accept-Encoding', |
| 1629 | b'Connection: close', |
| 1630 | b'Content-Type: text/html; charset=iso-8859-1', |
| 1631 | b'', |
| 1632 | b''] |
| 1633 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1634 | See the discussion of :ref:`ssl-security` below. |
| 1635 | |
| 1636 | |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1637 | Server-side operation |
| 1638 | ^^^^^^^^^^^^^^^^^^^^^ |
| 1639 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1640 | For server operation, typically you'll need to have a server certificate, and |
| 1641 | private key, each in a file. You'll first create a context holding the key |
| 1642 | and the certificate, so that clients can check your authenticity. Then |
| 1643 | you'll open a socket, bind it to a port, call :meth:`listen` on it, and start |
| 1644 | waiting for clients to connect:: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1645 | |
| 1646 | import socket, ssl |
| 1647 | |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1648 | context = ssl.SSLContext(ssl.PROTOCOL_SSLv23) |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1649 | context.load_cert_chain(certfile="mycertfile", keyfile="mykeyfile") |
| 1650 | |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1651 | bindsocket = socket.socket() |
| 1652 | bindsocket.bind(('myaddr.mydomain.com', 10023)) |
| 1653 | bindsocket.listen(5) |
| 1654 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1655 | When a client connects, you'll call :meth:`accept` on the socket to get the |
| 1656 | new socket from the other end, and use the context's :meth:`SSLContext.wrap_socket` |
| 1657 | method to create a server-side SSL socket for the connection:: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1658 | |
| 1659 | while True: |
Georg Brandl | 8a7e5da | 2011-01-02 19:07:51 +0000 | [diff] [blame] | 1660 | newsocket, fromaddr = bindsocket.accept() |
| 1661 | connstream = context.wrap_socket(newsocket, server_side=True) |
| 1662 | try: |
| 1663 | deal_with_client(connstream) |
| 1664 | finally: |
Antoine Pitrou | b205d58 | 2011-01-02 22:09:27 +0000 | [diff] [blame] | 1665 | connstream.shutdown(socket.SHUT_RDWR) |
Georg Brandl | 8a7e5da | 2011-01-02 19:07:51 +0000 | [diff] [blame] | 1666 | connstream.close() |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1667 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1668 | Then you'll read data from the ``connstream`` and do something with it till you |
Georg Brandl | 7f01a13 | 2009-09-16 15:58:14 +0000 | [diff] [blame] | 1669 | are finished with the client (or the client is finished with you):: |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1670 | |
| 1671 | def deal_with_client(connstream): |
Georg Brandl | 8a7e5da | 2011-01-02 19:07:51 +0000 | [diff] [blame] | 1672 | data = connstream.recv(1024) |
| 1673 | # empty data means the client is finished with us |
| 1674 | while data: |
| 1675 | if not do_something(connstream, data): |
| 1676 | # we'll assume do_something returns False |
| 1677 | # when we're finished with client |
| 1678 | break |
| 1679 | data = connstream.recv(1024) |
| 1680 | # finished with client |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1681 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1682 | And go back to listening for new client connections (of course, a real server |
| 1683 | would probably handle each client connection in a separate thread, or put |
Victor Stinner | 2961145 | 2014-10-10 12:52:43 +0200 | [diff] [blame] | 1684 | the sockets in :ref:`non-blocking mode <ssl-nonblocking>` and use an event loop). |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1685 | |
| 1686 | |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 1687 | .. _ssl-nonblocking: |
| 1688 | |
| 1689 | Notes on non-blocking sockets |
| 1690 | ----------------------------- |
| 1691 | |
Antoine Pitrou | b4bebda | 2014-04-29 10:03:28 +0200 | [diff] [blame] | 1692 | SSL sockets behave slightly different than regular sockets in |
| 1693 | non-blocking mode. When working with non-blocking sockets, there are |
| 1694 | thus several things you need to be aware of: |
| 1695 | |
| 1696 | - Most :class:`SSLSocket` methods will raise either |
| 1697 | :exc:`SSLWantWriteError` or :exc:`SSLWantReadError` instead of |
| 1698 | :exc:`BlockingIOError` if an I/O operation would |
| 1699 | block. :exc:`SSLWantReadError` will be raised if a read operation on |
| 1700 | the underlying socket is necessary, and :exc:`SSLWantWriteError` for |
| 1701 | a write operation on the underlying socket. Note that attempts to |
| 1702 | *write* to an SSL socket may require *reading* from the underlying |
| 1703 | socket first, and attempts to *read* from the SSL socket may require |
| 1704 | a prior *write* to the underlying socket. |
| 1705 | |
| 1706 | .. versionchanged:: 3.5 |
| 1707 | |
| 1708 | In earlier Python versions, the :meth:`!SSLSocket.send` method |
| 1709 | returned zero instead of raising :exc:`SSLWantWriteError` or |
| 1710 | :exc:`SSLWantReadError`. |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 1711 | |
| 1712 | - Calling :func:`~select.select` tells you that the OS-level socket can be |
| 1713 | read from (or written to), but it does not imply that there is sufficient |
| 1714 | data at the upper SSL layer. For example, only part of an SSL frame might |
| 1715 | have arrived. Therefore, you must be ready to handle :meth:`SSLSocket.recv` |
| 1716 | and :meth:`SSLSocket.send` failures, and retry after another call to |
| 1717 | :func:`~select.select`. |
| 1718 | |
Antoine Pitrou | 75e0338 | 2014-05-18 00:55:13 +0200 | [diff] [blame] | 1719 | - Conversely, since the SSL layer has its own framing, a SSL socket may |
| 1720 | still have data available for reading without :func:`~select.select` |
| 1721 | being aware of it. Therefore, you should first call |
| 1722 | :meth:`SSLSocket.recv` to drain any potentially available data, and then |
| 1723 | only block on a :func:`~select.select` call if still necessary. |
| 1724 | |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 1725 | (of course, similar provisions apply when using other primitives such as |
Antoine Pitrou | 75e0338 | 2014-05-18 00:55:13 +0200 | [diff] [blame] | 1726 | :func:`~select.poll`, or those in the :mod:`selectors` module) |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 1727 | |
| 1728 | - The SSL handshake itself will be non-blocking: the |
| 1729 | :meth:`SSLSocket.do_handshake` method has to be retried until it returns |
| 1730 | successfully. Here is a synopsis using :func:`~select.select` to wait for |
| 1731 | the socket's readiness:: |
| 1732 | |
| 1733 | while True: |
| 1734 | try: |
| 1735 | sock.do_handshake() |
| 1736 | break |
Antoine Pitrou | 873bf26 | 2011-10-27 23:59:03 +0200 | [diff] [blame] | 1737 | except ssl.SSLWantReadError: |
| 1738 | select.select([sock], [], []) |
| 1739 | except ssl.SSLWantWriteError: |
| 1740 | select.select([], [sock], []) |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 1741 | |
Victor Stinner | cfb2a0a | 2014-10-10 12:45:10 +0200 | [diff] [blame] | 1742 | .. seealso:: |
| 1743 | |
Victor Stinner | 2961145 | 2014-10-10 12:52:43 +0200 | [diff] [blame] | 1744 | The :mod:`asyncio` module supports :ref:`non-blocking SSL sockets |
| 1745 | <ssl-nonblocking>` and provides a |
Victor Stinner | cfb2a0a | 2014-10-10 12:45:10 +0200 | [diff] [blame] | 1746 | higher level API. It polls for events using the :mod:`selectors` module and |
| 1747 | handles :exc:`SSLWantWriteError`, :exc:`SSLWantReadError` and |
| 1748 | :exc:`BlockingIOError` exceptions. It runs the SSL handshake asynchronously |
| 1749 | as well. |
| 1750 | |
Antoine Pitrou | 6f5dcb1 | 2011-07-11 01:35:48 +0200 | [diff] [blame] | 1751 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1752 | Memory BIO Support |
| 1753 | ------------------ |
| 1754 | |
| 1755 | .. versionadded:: 3.5 |
| 1756 | |
| 1757 | Ever since the SSL module was introduced in Python 2.6, the :class:`SSLSocket` |
| 1758 | class has provided two related but distinct areas of functionality: |
| 1759 | |
| 1760 | - SSL protocol handling |
| 1761 | - Network IO |
| 1762 | |
| 1763 | The network IO API is identical to that provided by :class:`socket.socket`, |
| 1764 | from which :class:`SSLSocket` also inherits. This allows an SSL socket to be |
| 1765 | used as a drop-in replacement for a regular socket, making it very easy to add |
| 1766 | SSL support to an existing application. |
| 1767 | |
| 1768 | Combining SSL protocol handling and network IO usually works well, but there |
| 1769 | are some cases where it doesn't. An example is async IO frameworks that want to |
| 1770 | use a different IO multiplexing model than the "select/poll on a file |
| 1771 | descriptor" (readiness based) model that is assumed by :class:`socket.socket` |
| 1772 | and by the internal OpenSSL socket IO routines. This is mostly relevant for |
| 1773 | platforms like Windows where this model is not efficient. For this purpose, a |
| 1774 | reduced scope variant of :class:`SSLSocket` called :class:`SSLObject` is |
| 1775 | provided. |
| 1776 | |
| 1777 | .. class:: SSLObject |
| 1778 | |
| 1779 | A reduced-scope variant of :class:`SSLSocket` representing an SSL protocol |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1780 | instance that does not contain any network IO methods. This class is |
| 1781 | typically used by framework authors that want to implement asynchronous IO |
| 1782 | for SSL through memory buffers. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1783 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1784 | This class implements an interface on top of a low-level SSL object as |
| 1785 | implemented by OpenSSL. This object captures the state of an SSL connection |
| 1786 | but does not provide any network IO itself. IO needs to be performed through |
| 1787 | separate "BIO" objects which are OpenSSL's IO abstraction layer. |
| 1788 | |
| 1789 | An :class:`SSLObject` instance can be created using the |
| 1790 | :meth:`~SSLContext.wrap_bio` method. This method will create the |
| 1791 | :class:`SSLObject` instance and bind it to a pair of BIOs. The *incoming* |
| 1792 | BIO is used to pass data from Python to the SSL protocol instance, while the |
| 1793 | *outgoing* BIO is used to pass data the other way around. |
| 1794 | |
| 1795 | The following methods are available: |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1796 | |
Victor Stinner | 805b262 | 2014-10-10 12:49:08 +0200 | [diff] [blame] | 1797 | - :attr:`~SSLSocket.context` |
| 1798 | - :attr:`~SSLSocket.server_side` |
| 1799 | - :attr:`~SSLSocket.server_hostname` |
| 1800 | - :meth:`~SSLSocket.read` |
| 1801 | - :meth:`~SSLSocket.write` |
| 1802 | - :meth:`~SSLSocket.getpeercert` |
| 1803 | - :meth:`~SSLSocket.selected_npn_protocol` |
| 1804 | - :meth:`~SSLSocket.cipher` |
| 1805 | - :meth:`~SSLSocket.compression` |
| 1806 | - :meth:`~SSLSocket.pending` |
| 1807 | - :meth:`~SSLSocket.do_handshake` |
| 1808 | - :meth:`~SSLSocket.unwrap` |
| 1809 | - :meth:`~SSLSocket.get_channel_binding` |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1810 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1811 | When compared to :class:`SSLSocket`, this object lacks the following |
| 1812 | features: |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1813 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1814 | - Any form of network IO incluging methods such as ``recv()`` and |
| 1815 | ``send()``. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1816 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1817 | - There is no *do_handshake_on_connect* machinery. You must always manually |
| 1818 | call :meth:`~SSLSocket.do_handshake` to start the handshake. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1819 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1820 | - There is no handling of *suppress_ragged_eofs*. All end-of-file conditions |
| 1821 | that are in violation of the protocol are reported via the |
| 1822 | :exc:`SSLEOFError` exception. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1823 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1824 | - The method :meth:`~SSLSocket.unwrap` call does not return anything, |
| 1825 | unlike for an SSL socket where it returns the underlying socket. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1826 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1827 | - The *server_name_callback* callback passed to |
| 1828 | :meth:`SSLContext.set_servername_callback` will get an :class:`SSLObject` |
| 1829 | instance instead of a :class:`SSLSocket` instance as its first parameter. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1830 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1831 | Some notes related to the use of :class:`SSLObject`: |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1832 | |
Victor Stinner | 2debf15 | 2014-10-10 13:04:08 +0200 | [diff] [blame] | 1833 | - All IO on an :class:`SSLObject` is :ref:`non-blocking <ssl-nonblocking>`. |
| 1834 | This means that for example :meth:`~SSLSocket.read` will raise an |
| 1835 | :exc:`SSLWantReadError` if it needs more data than the incoming BIO has |
| 1836 | available. |
| 1837 | |
| 1838 | - There is no module-level ``wrap_bio()`` call like there is for |
| 1839 | :meth:`~SSLContext.wrap_socket`. An :class:`SSLObject` is always created |
| 1840 | via an :class:`SSLContext`. |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1841 | |
Victor Stinner | 805b262 | 2014-10-10 12:49:08 +0200 | [diff] [blame] | 1842 | An SSLObject communicates with the outside world using memory buffers. The |
| 1843 | class :class:`MemoryBIO` provides a memory buffer that can be used for this |
| 1844 | purpose. It wraps an OpenSSL memory BIO (Basic IO) object: |
| 1845 | |
| 1846 | .. class:: MemoryBIO |
| 1847 | |
| 1848 | A memory buffer that can be used to pass data between Python and an SSL |
| 1849 | protocol instance. |
| 1850 | |
| 1851 | .. attribute:: MemoryBIO.pending |
| 1852 | |
| 1853 | Return the number of bytes currently in the memory buffer. |
| 1854 | |
| 1855 | .. attribute:: MemoryBIO.eof |
| 1856 | |
| 1857 | A boolean indicating whether the memory BIO is current at the end-of-file |
| 1858 | position. |
| 1859 | |
| 1860 | .. method:: MemoryBIO.read(n=-1) |
| 1861 | |
| 1862 | Read up to *n* bytes from the memory buffer. If *n* is not specified or |
| 1863 | negative, all bytes are returned. |
| 1864 | |
| 1865 | .. method:: MemoryBIO.write(buf) |
| 1866 | |
| 1867 | Write the bytes from *buf* to the memory BIO. The *buf* argument must be an |
| 1868 | object supporting the buffer protocol. |
| 1869 | |
| 1870 | The return value is the number of bytes written, which is always equal to |
| 1871 | the length of *buf*. |
| 1872 | |
| 1873 | .. method:: MemoryBIO.write_eof() |
| 1874 | |
| 1875 | Write an EOF marker to the memory BIO. After this method has been called, it |
| 1876 | is illegal to call :meth:`~MemoryBIO.write`. The attribute :attr:`eof` will |
| 1877 | become true after all data currently in the buffer has been read. |
| 1878 | |
Antoine Pitrou | b1fdf47 | 2014-10-05 20:41:53 +0200 | [diff] [blame] | 1879 | |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1880 | .. _ssl-security: |
| 1881 | |
| 1882 | Security considerations |
| 1883 | ----------------------- |
| 1884 | |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1885 | Best defaults |
| 1886 | ^^^^^^^^^^^^^ |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1887 | |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1888 | For **client use**, if you don't have any special requirements for your |
| 1889 | security policy, it is highly recommended that you use the |
| 1890 | :func:`create_default_context` function to create your SSL context. |
| 1891 | It will load the system's trusted CA certificates, enable certificate |
Antoine Pitrou | f8cbbbb | 2014-03-23 16:31:08 +0100 | [diff] [blame] | 1892 | validation and hostname checking, and try to choose reasonably secure |
| 1893 | protocol and cipher settings. |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1894 | |
| 1895 | For example, here is how you would use the :class:`smtplib.SMTP` class to |
| 1896 | create a trusted, secure connection to a SMTP server:: |
| 1897 | |
| 1898 | >>> import ssl, smtplib |
| 1899 | >>> smtp = smtplib.SMTP("mail.python.org", port=587) |
| 1900 | >>> context = ssl.create_default_context() |
| 1901 | >>> smtp.starttls(context=context) |
| 1902 | (220, b'2.0.0 Ready to start TLS') |
| 1903 | |
| 1904 | If a client certificate is needed for the connection, it can be added with |
| 1905 | :meth:`SSLContext.load_cert_chain`. |
| 1906 | |
| 1907 | By contrast, if you create the SSL context by calling the :class:`SSLContext` |
Antoine Pitrou | f8cbbbb | 2014-03-23 16:31:08 +0100 | [diff] [blame] | 1908 | constructor yourself, it will not have certificate validation nor hostname |
| 1909 | checking enabled by default. If you do so, please read the paragraphs below |
| 1910 | to achieve a good security level. |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1911 | |
| 1912 | Manual settings |
| 1913 | ^^^^^^^^^^^^^^^ |
| 1914 | |
| 1915 | Verifying certificates |
| 1916 | '''''''''''''''''''''' |
| 1917 | |
Donald Stufft | 8b852f1 | 2014-05-20 12:58:38 -0400 | [diff] [blame] | 1918 | When calling the :class:`SSLContext` constructor directly, |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1919 | :const:`CERT_NONE` is the default. Since it does not authenticate the other |
| 1920 | peer, it can be insecure, especially in client mode where most of time you |
| 1921 | would like to ensure the authenticity of the server you're talking to. |
| 1922 | Therefore, when in client mode, it is highly recommended to use |
| 1923 | :const:`CERT_REQUIRED`. However, it is in itself not sufficient; you also |
Antoine Pitrou | 59fdd67 | 2010-10-08 10:37:08 +0000 | [diff] [blame] | 1924 | have to check that the server certificate, which can be obtained by calling |
| 1925 | :meth:`SSLSocket.getpeercert`, matches the desired service. For many |
| 1926 | protocols and applications, the service can be identified by the hostname; |
Christian Heimes | 1aa9a75 | 2013-12-02 02:41:19 +0100 | [diff] [blame] | 1927 | in this case, the :func:`match_hostname` function can be used. This common |
| 1928 | check is automatically performed when :attr:`SSLContext.check_hostname` is |
| 1929 | enabled. |
Antoine Pitrou | 152efa2 | 2010-05-16 18:19:27 +0000 | [diff] [blame] | 1930 | |
| 1931 | In server mode, if you want to authenticate your clients using the SSL layer |
| 1932 | (rather than using a higher-level authentication mechanism), you'll also have |
| 1933 | to specify :const:`CERT_REQUIRED` and similarly check the client certificate. |
| 1934 | |
| 1935 | .. note:: |
| 1936 | |
| 1937 | In client mode, :const:`CERT_OPTIONAL` and :const:`CERT_REQUIRED` are |
| 1938 | equivalent unless anonymous ciphers are enabled (they are disabled |
| 1939 | by default). |
Thomas Wouters | ed03b41 | 2007-08-28 21:37:11 +0000 | [diff] [blame] | 1940 | |
Antoine Pitrou | b521877 | 2010-05-21 09:56:06 +0000 | [diff] [blame] | 1941 | Protocol versions |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1942 | ''''''''''''''''' |
Antoine Pitrou | b521877 | 2010-05-21 09:56:06 +0000 | [diff] [blame] | 1943 | |
| 1944 | SSL version 2 is considered insecure and is therefore dangerous to use. If |
| 1945 | you want maximum compatibility between clients and servers, it is recommended |
| 1946 | to use :const:`PROTOCOL_SSLv23` as the protocol version and then disable |
| 1947 | SSLv2 explicitly using the :data:`SSLContext.options` attribute:: |
| 1948 | |
| 1949 | context = ssl.SSLContext(ssl.PROTOCOL_SSLv23) |
| 1950 | context.options |= ssl.OP_NO_SSLv2 |
| 1951 | |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1952 | The SSL context created above will allow SSLv3 and TLSv1 (and later, if |
| 1953 | supported by your system) connections, but not SSLv2. |
Antoine Pitrou | b521877 | 2010-05-21 09:56:06 +0000 | [diff] [blame] | 1954 | |
Antoine Pitrou | b7ffed8 | 2012-01-04 02:53:44 +0100 | [diff] [blame] | 1955 | Cipher selection |
Antoine Pitrou | c5e075f | 2014-03-22 18:19:11 +0100 | [diff] [blame] | 1956 | '''''''''''''''' |
Antoine Pitrou | b7ffed8 | 2012-01-04 02:53:44 +0100 | [diff] [blame] | 1957 | |
| 1958 | If you have advanced security requirements, fine-tuning of the ciphers |
| 1959 | enabled when negotiating a SSL session is possible through the |
| 1960 | :meth:`SSLContext.set_ciphers` method. Starting from Python 3.2.3, the |
| 1961 | ssl module disables certain weak ciphers by default, but you may want |
Donald Stufft | 79ccaa2 | 2014-03-21 21:33:34 -0400 | [diff] [blame] | 1962 | to further restrict the cipher choice. Be sure to read OpenSSL's documentation |
| 1963 | about the `cipher list format <http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT>`_. |
| 1964 | If you want to check which ciphers are enabled by a given cipher list, use the |
| 1965 | ``openssl ciphers`` command on your system. |
Antoine Pitrou | b7ffed8 | 2012-01-04 02:53:44 +0100 | [diff] [blame] | 1966 | |
Antoine Pitrou | 9eefe91 | 2013-11-17 15:35:33 +0100 | [diff] [blame] | 1967 | Multi-processing |
| 1968 | ^^^^^^^^^^^^^^^^ |
| 1969 | |
| 1970 | If using this module as part of a multi-processed application (using, |
| 1971 | for example the :mod:`multiprocessing` or :mod:`concurrent.futures` modules), |
| 1972 | be aware that OpenSSL's internal random number generator does not properly |
| 1973 | handle forked processes. Applications must change the PRNG state of the |
| 1974 | parent process if they use any SSL feature with :func:`os.fork`. Any |
| 1975 | successful call of :func:`~ssl.RAND_add`, :func:`~ssl.RAND_bytes` or |
| 1976 | :func:`~ssl.RAND_pseudo_bytes` is sufficient. |
| 1977 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1978 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1979 | .. seealso:: |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1980 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1981 | Class :class:`socket.socket` |
Georg Brandl | 4a6cf6c | 2013-10-06 18:20:31 +0200 | [diff] [blame] | 1982 | Documentation of underlying :mod:`socket` class |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1983 | |
Georg Brandl | 4a6cf6c | 2013-10-06 18:20:31 +0200 | [diff] [blame] | 1984 | `SSL/TLS Strong Encryption: An Introduction <http://httpd.apache.org/docs/trunk/en/ssl/ssl_intro.html>`_ |
| 1985 | Intro from the Apache webserver documentation |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1986 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1987 | `RFC 1422: Privacy Enhancement for Internet Electronic Mail: Part II: Certificate-Based Key Management <http://www.ietf.org/rfc/rfc1422>`_ |
| 1988 | Steve Kent |
Thomas Wouters | 47b49bf | 2007-08-30 22:15:33 +0000 | [diff] [blame] | 1989 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1990 | `RFC 1750: Randomness Recommendations for Security <http://www.ietf.org/rfc/rfc1750>`_ |
| 1991 | D. Eastlake et. al. |
Thomas Wouters | 89d996e | 2007-09-08 17:39:28 +0000 | [diff] [blame] | 1992 | |
Thomas Wouters | 1b7f891 | 2007-09-19 03:06:30 +0000 | [diff] [blame] | 1993 | `RFC 3280: Internet X.509 Public Key Infrastructure Certificate and CRL Profile <http://www.ietf.org/rfc/rfc3280>`_ |
| 1994 | Housley et. al. |
Antoine Pitrou | d532321 | 2010-10-22 18:19:07 +0000 | [diff] [blame] | 1995 | |
| 1996 | `RFC 4366: Transport Layer Security (TLS) Extensions <http://www.ietf.org/rfc/rfc4366>`_ |
| 1997 | Blake-Wilson et. al. |
Antoine Pitrou | 58ddc9d | 2013-01-05 21:20:29 +0100 | [diff] [blame] | 1998 | |
| 1999 | `RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2 <http://www.ietf.org/rfc/rfc5246>`_ |
| 2000 | T. Dierks et. al. |
| 2001 | |
| 2002 | `RFC 6066: Transport Layer Security (TLS) Extensions <http://www.ietf.org/rfc/rfc6066>`_ |
| 2003 | D. Eastlake |
| 2004 | |
| 2005 | `IANA TLS: Transport Layer Security (TLS) Parameters <http://www.iana.org/assignments/tls-parameters/tls-parameters.xml>`_ |
| 2006 | IANA |