| """ |
| PRNG management routines, thin wrappers. |
| |
| See the file RATIONALE for a short explanation of why this module was written. |
| """ |
| |
| from functools import partial |
| |
| from six import integer_types as _integer_types |
| |
| from OpenSSL._util import ( |
| ffi as _ffi, |
| lib as _lib, |
| exception_from_error_queue as _exception_from_error_queue) |
| |
| |
| class Error(Exception): |
| """ |
| An error occurred in an `OpenSSL.rand` API. |
| """ |
| |
| _raise_current_error = partial(_exception_from_error_queue, Error) |
| |
| _unspecified = object() |
| |
| _builtin_bytes = bytes |
| |
| def bytes(num_bytes): |
| """ |
| Get some random bytes as a string. |
| |
| :param num_bytes: The number of bytes to fetch |
| :return: A string of random bytes |
| """ |
| if not isinstance(num_bytes, _integer_types): |
| raise TypeError("num_bytes must be an integer") |
| |
| if num_bytes < 0: |
| raise ValueError("num_bytes must not be negative") |
| |
| result_buffer = _ffi.new("char[]", num_bytes) |
| result_code = _lib.RAND_bytes(result_buffer, num_bytes) |
| if result_code == -1: |
| # TODO: No tests for this code path. Triggering a RAND_bytes failure |
| # might involve supplying a custom ENGINE? That's hard. |
| _raise_current_error() |
| |
| return _ffi.buffer(result_buffer)[:] |
| |
| |
| |
| def add(buffer, entropy): |
| """ |
| Add data with a given entropy to the PRNG |
| |
| :param buffer: Buffer with random data |
| :param entropy: The entropy (in bytes) measurement of the buffer |
| :return: None |
| """ |
| if not isinstance(buffer, _builtin_bytes): |
| raise TypeError("buffer must be a byte string") |
| |
| if not isinstance(entropy, int): |
| raise TypeError("entropy must be an integer") |
| |
| # TODO Nothing tests this call actually being made, or made properly. |
| _lib.RAND_add(buffer, len(buffer), entropy) |
| |
| |
| |
| def seed(buffer): |
| """ |
| Alias for rand_add, with entropy equal to length |
| |
| :param buffer: Buffer with random data |
| :return: None |
| """ |
| if not isinstance(buffer, _builtin_bytes): |
| raise TypeError("buffer must be a byte string") |
| |
| # TODO Nothing tests this call actually being made, or made properly. |
| _lib.RAND_seed(buffer, len(buffer)) |
| |
| |
| |
| def status(): |
| """ |
| Retrieve the status of the PRNG |
| |
| :return: True if the PRNG is seeded enough, false otherwise |
| """ |
| return _lib.RAND_status() |
| |
| |
| |
| def egd(path, bytes=_unspecified): |
| """ |
| Query an entropy gathering daemon (EGD) for random data and add it to the |
| PRNG. I haven't found any problems when the socket is missing, the function |
| just returns 0. |
| |
| :param path: The path to the EGD socket |
| :param bytes: (optional) The number of bytes to read, default is 255 |
| :returns: The number of bytes read (NB: a value of 0 isn't necessarily an |
| error, check rand.status()) |
| """ |
| if not isinstance(path, _builtin_bytes): |
| raise TypeError("path must be a byte string") |
| |
| if bytes is _unspecified: |
| bytes = 255 |
| elif not isinstance(bytes, int): |
| raise TypeError("bytes must be an integer") |
| |
| return _lib.RAND_egd_bytes(path, bytes) |
| |
| |
| |
| def cleanup(): |
| """ |
| Erase the memory used by the PRNG. |
| |
| :return: None |
| """ |
| # TODO Nothing tests this call actually being made, or made properly. |
| _lib.RAND_cleanup() |
| |
| |
| |
| def load_file(filename, maxbytes=_unspecified): |
| """ |
| Seed the PRNG with data from a file |
| |
| :param filename: The file to read data from |
| :param maxbytes: (optional) The number of bytes to read, default is |
| to read the entire file |
| :return: The number of bytes read |
| """ |
| if not isinstance(filename, _builtin_bytes): |
| raise TypeError("filename must be a string") |
| |
| if maxbytes is _unspecified: |
| maxbytes = -1 |
| elif not isinstance(maxbytes, int): |
| raise TypeError("maxbytes must be an integer") |
| |
| return _lib.RAND_load_file(filename, maxbytes) |
| |
| |
| |
| def write_file(filename): |
| """ |
| Save PRNG state to a file |
| |
| :param filename: The file to write data to |
| :return: The number of bytes written |
| """ |
| if not isinstance(filename, _builtin_bytes): |
| raise TypeError("filename must be a string") |
| |
| return _lib.RAND_write_file(filename) |
| |
| |
| # TODO There are no tests for screen at all |
| def screen(): |
| """ |
| Add the current contents of the screen to the PRNG state. Availability: |
| Windows. |
| |
| :return: None |
| """ |
| _lib.RAND_screen() |
| |
| if getattr(_lib, 'RAND_screen', None) is None: |
| del screen |
| |
| |
| # TODO There are no tests for the RAND strings being loaded, whatever that |
| # means. |
| _lib.ERR_load_RAND_strings() |