add support for signature_algorithm in x509.Certificate
diff --git a/docs/x509.rst b/docs/x509.rst
index 0298d94..8043b36 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -182,6 +182,18 @@
The :class:`Name` of the subject.
+ .. attribute:: signature_algorithm
+
+ :type: :class:`ObjectIdentifier`
+
+ An :class:`ObjectIdentifier` instance corresponding to the signature
+ algorithm used to sign the certificate. This is both the digest
+ used as well as the asymmetric type.
+
+ .. doctest::
+
+ >>> cert.signature_algorithm
+ <ObjectIdentifier(oid=1.2.840.113549.1.1.11, name=sha256WithRSAEncryption)>
.. class:: Name
@@ -266,6 +278,9 @@
X.509 elements are frequently identified by :class:`ObjectIdentifier`
instances. The following common OIDs are available as constants.
+Name OIDs
+~~~~~~~~~
+
.. data:: OID_COMMON_NAME
Corresponds to the dotted string ``"2.5.4.3"``. Historically the domain
@@ -346,6 +361,75 @@
Corresponds to the dotted string ``"1.2.840.113549.1.9.1"``. This OID is
typically seen in X.509 names.
+Signature Algorithm OIDs
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. data:: OID_MD5_WITH_RSA
+
+ Corresponds to the dotted string ``"1.2.840.113549.1.1.4"``. This is
+ an MD5 digest signed by an RSA key.
+
+.. data:: OID_SHA1_WITH_RSA
+
+ Corresponds to the dotted string ``"1.2.840.113549.1.1.5"``. This is
+ a SHA1 digest signed by an RSA key.
+
+.. data:: OID_SHA224_WITH_RSA
+
+ Corresponds to the dotted string ``"1.2.840.113549.1.1.14"``. This is
+ a SHA224 digest signed by an RSA key.
+
+.. data:: OID_SHA256_WITH_RSA
+
+ Corresponds to the dotted string ``"1.2.840.113549.1.1.11"``. This is
+ a SHA256 digest signed by an RSA key.
+
+.. data:: OID_SHA384_WITH_RSA
+
+ Corresponds to the dotted string ``"1.2.840.113549.1.1.12"``. This is
+ a SHA384 digest signed by an RSA key.
+
+.. data:: OID_SHA512_WITH_RSA
+
+ Corresponds to the dotted string ``"1.2.840.113549.1.1.13"``. This is
+ a SHA512 digest signed by an RSA key.
+
+.. data:: OID_ECDSA_WITH_SHA224
+
+ Corresponds to the dotted string ``"1.2.840.10045.4.3.1"``. This is
+ a SHA224 digest signed by an ECDSA key.
+
+.. data:: OID_ECDSA_WITH_SHA256
+
+ Corresponds to the dotted string ``"1.2.840.10045.4.3.2"``. This is
+ a SHA256 digest signed by an ECDSA key.
+
+.. data:: OID_ECDSA_WITH_SHA384
+
+ Corresponds to the dotted string ``"1.2.840.10045.4.3.3"``. This is
+ a SHA384 digest signed by an ECDSA key.
+
+.. data:: OID_ECDSA_WITH_SHA512
+
+ Corresponds to the dotted string ``"1.2.840.10045.4.3.4"``. This is
+ a SHA512 digest signed by an ECDSA key.
+
+.. data:: OID_DSA_WITH_SHA1
+
+ Corresponds to the dotted string ``"1.2.840.10040.4.3"``. This is
+ a SHA1 digest signed by a DSA key.
+
+.. data:: OID_DSA_WITH_SHA224
+
+ Corresponds to the dotted string ``"2.16.840.1.101.3.4.3.1"``. This is
+ a SHA224 digest signed by a DSA key.
+
+.. data:: OID_DSA_WITH_SHA256
+
+ Corresponds to the dotted string ``2.16.840.1.101.3.4.3.2"``. This is
+ a SHA256 digest signed by a DSA key.
+
+
Exceptions
~~~~~~~~~~