diff options
Diffstat (limited to 'frozen_deps/Crypto/Random/Fortuna')
| -rw-r--r-- | frozen_deps/Crypto/Random/Fortuna/FortunaAccumulator.py | 171 | ||||
| -rw-r--r-- | frozen_deps/Crypto/Random/Fortuna/FortunaGenerator.py | 132 | ||||
| -rw-r--r-- | frozen_deps/Crypto/Random/Fortuna/SHAd256.py | 98 | ||||
| -rw-r--r-- | frozen_deps/Crypto/Random/Fortuna/__init__.py | 0 |
4 files changed, 401 insertions, 0 deletions
diff --git a/frozen_deps/Crypto/Random/Fortuna/FortunaAccumulator.py b/frozen_deps/Crypto/Random/Fortuna/FortunaAccumulator.py new file mode 100644 index 0000000..5c6beb0 --- /dev/null +++ b/frozen_deps/Crypto/Random/Fortuna/FortunaAccumulator.py @@ -0,0 +1,171 @@ +# -*- coding: ascii -*- +# +# FortunaAccumulator.py : Fortuna's internal accumulator +# +# Written in 2008 by Dwayne C. Litzenberger <[email protected]> +# +# =================================================================== +# The contents of this file are dedicated to the public domain. To +# the extent that dedication to the public domain is not available, +# everyone is granted a worldwide, perpetual, royalty-free, +# non-exclusive license to exercise all rights associated with the +# contents of this file for any purpose whatsoever. +# No rights are reserved. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS +# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN +# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +# SOFTWARE. +# =================================================================== + +__revision__ = "$Id$" + +import sys +if sys.version_info[0] == 2 and sys.version_info[1] == 1: + from Crypto.Util.py21compat import * +from Crypto.Util.py3compat import * + +from binascii import b2a_hex +import time +import warnings + +from Crypto.pct_warnings import ClockRewindWarning +from . import SHAd256 + +from . import FortunaGenerator + +class FortunaPool(object): + """Fortuna pool type + + This object acts like a hash object, with the following differences: + + - It keeps a count (the .length attribute) of the number of bytes that + have been added to the pool + - It supports a .reset() method for in-place reinitialization + - The method to add bytes to the pool is .append(), not .update(). + """ + + digest_size = SHAd256.digest_size + + def __init__(self): + self.reset() + + def append(self, data): + self._h.update(data) + self.length += len(data) + + def digest(self): + return self._h.digest() + + def hexdigest(self): + if sys.version_info[0] == 2: + return b2a_hex(self.digest()) + else: + return b2a_hex(self.digest()).decode() + + def reset(self): + self._h = SHAd256.new() + self.length = 0 + +def which_pools(r): + """Return a list of pools indexes (in range(32)) that are to be included during reseed number r. + + According to _Practical Cryptography_, chapter 10.5.2 "Pools": + + "Pool P_i is included if 2**i is a divisor of r. Thus P_0 is used + every reseed, P_1 every other reseed, P_2 every fourth reseed, etc." + """ + # This is a separate function so that it can be unit-tested. + assert r >= 1 + retval = [] + mask = 0 + for i in range(32): + # "Pool P_i is included if 2**i is a divisor of [reseed_count]" + if (r & mask) == 0: + retval.append(i) + else: + break # optimization. once this fails, it always fails + mask = (mask << 1) | 1 + return retval + +class FortunaAccumulator(object): + + # An estimate of how many bytes we must append to pool 0 before it will + # contain 128 bits of entropy (with respect to an attack). We reseed the + # generator only after pool 0 contains `min_pool_size` bytes. Note that + # unlike with some other PRNGs, Fortuna's security does not rely on the + # accuracy of this estimate---we can accord to be optimistic here. + min_pool_size = 64 # size in bytes + + # If an attacker can predict some (but not all) of our entropy sources, the + # `min_pool_size` check may not be sufficient to prevent a successful state + # compromise extension attack. To resist this attack, Fortuna spreads the + # input across 32 pools, which are then consumed (to reseed the output + # generator) with exponentially decreasing frequency. + # + # In order to prevent an attacker from gaining knowledge of all 32 pools + # before we have a chance to fill them with enough information that the + # attacker cannot predict, we impose a rate limit of 10 reseeds/second (one + # per 100 ms). This ensures that a hypothetical 33rd pool would only be + # needed after a minimum of 13 years of sustained attack. + reseed_interval = 0.100 # time in seconds + + def __init__(self): + self.reseed_count = 0 + self.generator = FortunaGenerator.AESGenerator() + self.last_reseed = None + + # Initialize 32 FortunaPool instances. + # NB: This is _not_ equivalent to [FortunaPool()]*32, which would give + # us 32 references to the _same_ FortunaPool instance (and cause the + # assertion below to fail). + self.pools = [FortunaPool() for i in range(32)] # 32 pools + assert(self.pools[0] is not self.pools[1]) + + def _forget_last_reseed(self): + # This is not part of the standard Fortuna definition, and using this + # function frequently can weaken Fortuna's ability to resist a state + # compromise extension attack, but we need this in order to properly + # implement Crypto.Random.atfork(). Otherwise, forked child processes + # might continue to use their parent's PRNG state for up to 100ms in + # some cases. (e.g. CVE-2013-1445) + self.last_reseed = None + + def random_data(self, bytes): + current_time = time.time() + if (self.last_reseed is not None and self.last_reseed > current_time): # Avoid float comparison to None to make Py3k happy + warnings.warn("Clock rewind detected. Resetting last_reseed.", ClockRewindWarning) + self.last_reseed = None + if (self.pools[0].length >= self.min_pool_size and + (self.last_reseed is None or + current_time > self.last_reseed + self.reseed_interval)): + self._reseed(current_time) + # The following should fail if we haven't seeded the pool yet. + return self.generator.pseudo_random_data(bytes) + + def _reseed(self, current_time=None): + if current_time is None: + current_time = time.time() + seed = [] + self.reseed_count += 1 + self.last_reseed = current_time + for i in which_pools(self.reseed_count): + seed.append(self.pools[i].digest()) + self.pools[i].reset() + + seed = b("").join(seed) + self.generator.reseed(seed) + + def add_random_event(self, source_number, pool_number, data): + assert 1 <= len(data) <= 32 + assert 0 <= source_number <= 255 + assert 0 <= pool_number <= 31 + self.pools[pool_number].append(bchr(source_number)) + self.pools[pool_number].append(bchr(len(data))) + self.pools[pool_number].append(data) + +# vim:set ts=4 sw=4 sts=4 expandtab: diff --git a/frozen_deps/Crypto/Random/Fortuna/FortunaGenerator.py b/frozen_deps/Crypto/Random/Fortuna/FortunaGenerator.py new file mode 100644 index 0000000..489c81e --- /dev/null +++ b/frozen_deps/Crypto/Random/Fortuna/FortunaGenerator.py @@ -0,0 +1,132 @@ +# -*- coding: ascii -*- +# +# FortunaGenerator.py : Fortuna's internal PRNG +# +# Written in 2008 by Dwayne C. Litzenberger <[email protected]> +# +# =================================================================== +# The contents of this file are dedicated to the public domain. To +# the extent that dedication to the public domain is not available, +# everyone is granted a worldwide, perpetual, royalty-free, +# non-exclusive license to exercise all rights associated with the +# contents of this file for any purpose whatsoever. +# No rights are reserved. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS +# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN +# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +# SOFTWARE. +# =================================================================== + +__revision__ = "$Id$" + +import sys +if sys.version_info[0] is 2 and sys.version_info[1] is 1: + from Crypto.Util.py21compat import * +from Crypto.Util.py3compat import * + +import struct + +from Crypto.Util.number import ceil_shift, exact_log2, exact_div +from Crypto.Util import Counter +from Crypto.Cipher import AES + +from . import SHAd256 + +class AESGenerator(object): + """The Fortuna "generator" + + This is used internally by the Fortuna PRNG to generate arbitrary amounts + of pseudorandom data from a smaller amount of seed data. + + The output is generated by running AES-256 in counter mode and re-keying + after every mebibyte (2**16 blocks) of output. + """ + + block_size = AES.block_size # output block size in octets (128 bits) + key_size = 32 # key size in octets (256 bits) + + # Because of the birthday paradox, we expect to find approximately one + # collision for every 2**64 blocks of output from a real random source. + # However, this code generates pseudorandom data by running AES in + # counter mode, so there will be no collisions until the counter + # (theoretically) wraps around at 2**128 blocks. Thus, in order to prevent + # Fortuna's pseudorandom output from deviating perceptibly from a true + # random source, Ferguson and Schneier specify a limit of 2**16 blocks + # without rekeying. + max_blocks_per_request = 2**16 # Allow no more than this number of blocks per _pseudo_random_data request + + _four_kiblocks_of_zeros = b("\0") * block_size * 4096 + + def __init__(self): + self.counter = Counter.new(nbits=self.block_size*8, initial_value=0, little_endian=True) + self.key = None + + # Set some helper constants + self.block_size_shift = exact_log2(self.block_size) + assert (1 << self.block_size_shift) == self.block_size + + self.blocks_per_key = exact_div(self.key_size, self.block_size) + assert self.key_size == self.blocks_per_key * self.block_size + + self.max_bytes_per_request = self.max_blocks_per_request * self.block_size + + def reseed(self, seed): + if self.key is None: + self.key = b("\0") * self.key_size + + self._set_key(SHAd256.new(self.key + seed).digest()) + self.counter() # increment counter + assert len(self.key) == self.key_size + + def pseudo_random_data(self, bytes): + assert bytes >= 0 + + num_full_blocks = bytes >> 20 + remainder = bytes & ((1<<20)-1) + + retval = [] + for i in range(num_full_blocks): + retval.append(self._pseudo_random_data(1<<20)) + retval.append(self._pseudo_random_data(remainder)) + + return b("").join(retval) + + def _set_key(self, key): + self.key = key + self._cipher = AES.new(key, AES.MODE_CTR, counter=self.counter) + + def _pseudo_random_data(self, bytes): + if not (0 <= bytes <= self.max_bytes_per_request): + raise AssertionError("You cannot ask for more than 1 MiB of data per request") + + num_blocks = ceil_shift(bytes, self.block_size_shift) # num_blocks = ceil(bytes / self.block_size) + + # Compute the output + retval = self._generate_blocks(num_blocks)[:bytes] + + # Switch to a new key to avoid later compromises of this output (i.e. + # state compromise extension attacks) + self._set_key(self._generate_blocks(self.blocks_per_key)) + + assert len(retval) == bytes + assert len(self.key) == self.key_size + + return retval + + def _generate_blocks(self, num_blocks): + if self.key is None: + raise AssertionError("generator must be seeded before use") + assert 0 <= num_blocks <= self.max_blocks_per_request + retval = [] + for i in range(num_blocks >> 12): # xrange(num_blocks / 4096) + retval.append(self._cipher.encrypt(self._four_kiblocks_of_zeros)) + remaining_bytes = (num_blocks & 4095) << self.block_size_shift # (num_blocks % 4095) * self.block_size + retval.append(self._cipher.encrypt(self._four_kiblocks_of_zeros[:remaining_bytes])) + return b("").join(retval) + +# vim:set ts=4 sw=4 sts=4 expandtab: diff --git a/frozen_deps/Crypto/Random/Fortuna/SHAd256.py b/frozen_deps/Crypto/Random/Fortuna/SHAd256.py new file mode 100644 index 0000000..2e135c9 --- /dev/null +++ b/frozen_deps/Crypto/Random/Fortuna/SHAd256.py @@ -0,0 +1,98 @@ +# -*- coding: ascii -*- +# +# Random/Fortuna/SHAd256.py : SHA_d-256 hash function implementation +# +# Written in 2008 by Dwayne C. Litzenberger <[email protected]> +# +# =================================================================== +# The contents of this file are dedicated to the public domain. To +# the extent that dedication to the public domain is not available, +# everyone is granted a worldwide, perpetual, royalty-free, +# non-exclusive license to exercise all rights associated with the +# contents of this file for any purpose whatsoever. +# No rights are reserved. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS +# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN +# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +# SOFTWARE. +# =================================================================== + +"""\ +SHA_d-256 hash function implementation. + +This module should comply with PEP 247. +""" + +__revision__ = "$Id$" +__all__ = ['new', 'digest_size'] + +import sys +if sys.version_info[0] == 2 and sys.version_info[1] == 1: + from Crypto.Util.py21compat import * +from Crypto.Util.py3compat import * + +from binascii import b2a_hex + +from Crypto.Hash import SHA256 + +assert SHA256.digest_size == 32 + +class _SHAd256(object): + """SHA-256, doubled. + + Returns SHA-256(SHA-256(data)). + """ + + digest_size = SHA256.digest_size + + _internal = object() + + def __init__(self, internal_api_check, sha256_hash_obj): + if internal_api_check is not self._internal: + raise AssertionError("Do not instantiate this class directly. Use %s.new()" % (__name__,)) + self._h = sha256_hash_obj + + # PEP 247 "copy" method + def copy(self): + """Return a copy of this hashing object""" + return _SHAd256(SHAd256._internal, self._h.copy()) + + # PEP 247 "digest" method + def digest(self): + """Return the hash value of this object as a binary string""" + retval = SHA256.new(self._h.digest()).digest() + assert len(retval) == 32 + return retval + + # PEP 247 "hexdigest" method + def hexdigest(self): + """Return the hash value of this object as a (lowercase) hexadecimal string""" + retval = b2a_hex(self.digest()) + assert len(retval) == 64 + if sys.version_info[0] == 2: + return retval + else: + return retval.decode() + + # PEP 247 "update" method + def update(self, data): + self._h.update(data) + +# PEP 247 module-level "digest_size" variable +digest_size = _SHAd256.digest_size + +# PEP 247 module-level "new" function +def new(data=None): + """Return a new SHAd256 hashing object""" + if not data: + data=b("") + sha = _SHAd256(_SHAd256._internal, SHA256.new(data)) + sha.new = globals()['new'] + return sha + +# vim:set ts=4 sw=4 sts=4 expandtab: diff --git a/frozen_deps/Crypto/Random/Fortuna/__init__.py b/frozen_deps/Crypto/Random/Fortuna/__init__.py new file mode 100644 index 0000000..e69de29 --- /dev/null +++ b/frozen_deps/Crypto/Random/Fortuna/__init__.py |