openmedialibrary_platform_w.../Lib/site-packages/OpenSSL/rand.py

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2016-01-31 14:44:46 +00:00
"""
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,
path_string as _path_string)
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 (``bytes`` or ``unicode``).
:param maxbytes: (optional) The number of bytes to read, default is to read
the entire file
:return: The number of bytes read
"""
filename = _path_string(filename)
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 (``bytes`` or ``unicode``).
:return: The number of bytes written
"""
filename = _path_string(filename)
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()