Replace PBKDF2 class by python stdlib implementation
hashlib.pbkdf2_hmac has been backported to Python 2.7 (see PEP 466). In order to avoid reinventing the wheel and to include less third party code we switch to the stdlib implementation.
This commit is contained in:
Dominik
@@ -19,6 +19,8 @@
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import sys, binascii, random, logging
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from struct import pack
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from binascii import b2a_hex, a2b_hex
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from base64 import b64encode
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from hashlib import pbkdf2_hmac
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from random import randint
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from virtualsmartcard.utils import inttostring, hexdump
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import string, re
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@@ -271,196 +273,6 @@ def calculate_MAC(session_key, message, iv=CYBERFLEX_IV):
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return crypted[len(padded) - cipher.block_size : ]
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###########################################################################
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# PBKDF2.py - PKCS#5 v2.0 Password-Based Key Derivation
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#
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# Copyright (C) 2007, 2008 Dwayne C. Litzenberger <dlitz@dlitz.net>
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# All rights reserved.
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#
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# Permission to use, copy, modify, and distribute this software and its
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# documentation for any purpose and without fee is hereby granted,
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# provided that the above copyright notice appear in all copies and that
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# both that copyright notice and this permission notice appear in
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# supporting documentation.
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#
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# THE AUTHOR PROVIDES THIS SOFTWARE ``AS IS'' AND ANY EXPRESSED OR
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# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# Country of origin: Canada
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#
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###########################################################################
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# Sample PBKDF2 usage:
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# from Crypto.Cipher import AES
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# from PBKDF2 import PBKDF2
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# import os
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#
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# salt = os.urandom(8) # 64-bit salt
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# key = PBKDF2("This passphrase is a secret.", salt).read(32) # 256-bit key
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# iv = os.urandom(16) # 128-bit IV
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# cipher = AES.new(key, AES.MODE_CBC, iv)
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# ...
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#
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# Sample crypt() usage:
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# from PBKDF2 import crypt
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# pwhash = crypt("secret")
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# alleged_pw = raw_input("Enter password: ")
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# if pwhash == crypt(alleged_pw, pwhash):
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# print "Password good"
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# else:
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# print "Invalid password"
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#
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###########################################################################
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# History:
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#
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# 2007-07-27 Dwayne C. Litzenberger <dlitz@dlitz.net>
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# - Initial Release (v1.0)
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#
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# 2007-07-31 Dwayne C. Litzenberger <dlitz@dlitz.net>
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# - Bugfix release (v1.1)
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# - SECURITY: The PyCrypto XOR cipher (used, if available, in the _strxor
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# function in the previous release) silently truncates all keys to 64
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# bytes. The way it was used in the previous release, this would only be
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# problem if the pseudorandom function that returned values larger than
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# 64 bytes (so SHA1, SHA256 and SHA512 are fine), but I don't like
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# anything that silently reduces the security margin from what is
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# expected.
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#
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# 2008-06-17 Dwayne C. Litzenberger <dlitz@dlitz.net>
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# - Compatibility release (v1.2)
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# - Add support for older versions of Python (2.2 and 2.3).
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#
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###########################################################################
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__version__ = "1.2"
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def strxor(a, b):
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return "".join([chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b)])
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def b64encode(data, chars="+/"):
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tt = string.maketrans("+/", chars)
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return data.encode('base64').replace("\n", "").translate(tt)
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class PBKDF2(object):
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"""PBKDF2.py : PKCS#5 v2.0 Password-Based Key Derivation
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This implementation takes a passphrase and a salt (and optionally an
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iteration count, a digest module, and a MAC module) and provides a
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file-like object from which an arbitrarily-sized key can be read.
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If the passphrase and/or salt are unicode objects, they are encoded as
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UTF-8 before they are processed.
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The idea behind PBKDF2 is to derive a cryptographic key from a
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passphrase and a salt.
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PBKDF2 may also be used as a strong salted password hash. The
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'crypt' function is provided for that purpose.
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Remember: Keys generated using PBKDF2 are only as strong as the
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passphrases they are derived from.
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"""
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def __init__(self, passphrase, salt, iterations=1000,
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digestmodule=SHA1, macmodule=HMAC):
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self.__macmodule = macmodule
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self.__digestmodule = digestmodule
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self._setup(passphrase, salt, iterations, self._pseudorandom)
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def _pseudorandom(self, key, msg):
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"""Pseudorandom function. e.g. HMAC-SHA1"""
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return self.__macmodule.new(key=key, msg=msg,
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digestmod=self.__digestmodule).digest()
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def read(self, bytes):
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"""Read the specified number of key bytes."""
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if self.closed:
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raise ValueError("file-like object is closed")
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size = len(self.__buf)
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blocks = [self.__buf]
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i = self.__blockNum
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while size < bytes:
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i += 1
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if i > 0xffffffffL or i < 1:
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# We could return "" here, but
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raise OverflowError("derived key too long")
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block = self.__f(i)
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blocks.append(block)
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size += len(block)
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buf = "".join(blocks)
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retval = buf[:bytes]
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self.__buf = buf[bytes:]
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self.__blockNum = i
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return retval
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def __f(self, i):
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# i must fit within 32 bits
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assert 1 <= i <= 0xffffffffL
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U = self.__prf(self.__passphrase, self.__salt + pack("!L", i))
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result = U
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for j in xrange(2, 1+self.__iterations):
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U = self.__prf(self.__passphrase, U)
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result = strxor(result, U)
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return result
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def hexread(self, octets):
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"""Read the specified number of octets. Return them as hexadecimal.
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Note that len(obj.hexread(n)) == 2*n.
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"""
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return b2a_hex(self.read(octets))
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def _setup(self, passphrase, salt, iterations, prf):
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# Sanity checks:
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# passphrase and salt must be str or unicode (in the latter
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# case, we convert to UTF-8)
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if isinstance(passphrase, unicode):
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passphrase = passphrase.encode("UTF-8")
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if not isinstance(passphrase, str):
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raise TypeError("passphrase must be str or unicode")
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if isinstance(salt, unicode):
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salt = salt.encode("UTF-8")
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if not isinstance(salt, str):
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raise TypeError("salt must be str or unicode")
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# iterations must be an integer >= 1
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if not isinstance(iterations, (int, long)):
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raise TypeError("iterations must be an integer")
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if iterations < 1:
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raise ValueError("iterations must be at least 1")
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# prf must be callable
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if not callable(prf):
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raise TypeError("prf must be callable")
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self.__passphrase = passphrase
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self.__salt = salt
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self.__iterations = iterations
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self.__prf = prf
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self.__blockNum = 0
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self.__buf = ""
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self.closed = False
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def close(self):
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"""Close the stream."""
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if not self.closed:
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del self.__passphrase
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del self.__salt
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del self.__iterations
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del self.__prf
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del self.__blockNum
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del self.__buf
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self.closed = True
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def crypt(word, salt=None, iterations=None):
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"""PBKDF2-based unix crypt(3) replacement.
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@@ -510,7 +322,7 @@ def crypt(word, salt=None, iterations=None):
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salt = "$p5k2$$" + salt
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else:
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salt = "$p5k2$%x$%s" % (iterations, salt)
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rawhash = PBKDF2(word, salt, iterations).read(24)
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rawhash = pbkdf2_hmac('sha1', salt, word, iterations, 24)
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# return salt + "$" + b64encode(rawhash, "./") DO: Original return line
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return salt + "$" + rawhash
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