1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
"""
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()
|
