Commit 1030d66a authored by Paul McMillan's avatar Paul McMillan
Browse files

Fixed #17481. pbkdf2 hashes no longer ommit leading zeros. 

Some existing user passwords may need to be reset or converted 
after this change. See the 1.4-beta release notes for more details.

Thanks bhuztez for the report and initial patch, claudep for the test.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@17418 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent ccbadbc5

django/utils/crypto.py

+15 −15
Original line number Diff line number Diff line
@@ -10,8 +10,8 @@ import operator 
from django.conf import settings





trans_5c = "".join([chr(x ^ 0x5C) for x in xrange(256)])

trans_36 = "".join([chr(x ^ 0x36) for x in xrange(256)])

_trans_5c = "".join([chr(x ^ 0x5C) for x in xrange(256)])

_trans_36 = "".join([chr(x ^ 0x36) for x in xrange(256)])





def salted_hmac(key_salt, value, secret=None):
@@ -66,7 +66,7 @@ def constant_time_compare(val1, val2): 
    return result == 0





def bin_to_long(x):

def _bin_to_long(x):

    """

    Convert a binary string into a long integer
@@ -75,17 +75,15 @@ def bin_to_long(x): 
    return long(x.encode('hex'), 16)





def long_to_bin(x):

def _long_to_bin(x, hex_format_string):

    """

    Convert a long integer into a binary string

    Convert a long integer into a binary string.

    hex_format_string is like "%020x" for padding 10 characters.

    """

    hex = "%x" % (x)

    if len(hex) % 2 == 1:

        hex = '0' + hex

    return binascii.unhexlify(hex)

    return binascii.unhexlify(hex_format_string % x)





def fast_hmac(key, msg, digest):

def _fast_hmac(key, msg, digest):

    """

    A trimmed down version of Python's HMAC implementation

    """
@@ -93,9 +91,9 @@ def fast_hmac(key, msg, digest): 
    if len(key) > dig1.block_size:

        key = digest(key).digest()

    key += chr(0) * (dig1.block_size - len(key))

    dig1.update(key.translate(trans_36))

    dig1.update(key.translate(_trans_36))

    dig1.update(msg)

    dig2.update(key.translate(trans_5c))

    dig2.update(key.translate(_trans_5c))

    dig2.update(dig1.digest())

    return dig2
@@ -123,13 +121,15 @@ def pbkdf2(password, salt, iterations, dklen=0, digest=None): 
    l = -(-dklen // hlen)

    r = dklen - (l - 1) * hlen



    hex_format_string = "%%0%ix" % (hlen * 2)



    def F(i):

        def U():

            u = salt + struct.pack('>I', i)

            for j in xrange(int(iterations)):

                u = fast_hmac(password, u, digest).digest()

                yield bin_to_long(u)

        return long_to_bin(reduce(operator.xor, U()))

                u = _fast_hmac(password, u, digest).digest()

                yield _bin_to_long(u)

        return _long_to_bin(reduce(operator.xor, U()), hex_format_string)



    T = [F(x) for x in range(1, l + 1)]

    return ''.join(T[:-1]) + T[-1][:r]

tests/regressiontests/utils/crypto.py

+19 −4
Original line number Diff line number Diff line
@@ -108,6 +108,17 @@ class TestUtilsCryptoPBKDF2(unittest.TestCase): 
                       "c4007d5298f9033c0241d5ab69305e7b64eceeb8d"

                       "834cfec"),

        },

        # Check leading zeros are not stripped (#17481) 

        {

            "args": { 

                "password": chr(186), 

                "salt": "salt", 

                "iterations": 1, 

                "dklen": 20, 

                "digest": hashlib.sha1, 

            }, 

            "result": '0053d3b91a7f1e54effebd6d68771e8a6e0b2c5b',

        },

    ]



    def test_public_vectors(self):
@@ -125,11 +136,15 @@ class TestUtilsCryptoPBKDF2(unittest.TestCase): 
        Theory: If you run with 100 iterations, it should take 100

        times as long as running with 1 iteration.

        """

        n1, n2 = 1000, 100000

        elapsed = lambda f: timeit.Timer(f, 'from django.utils.crypto import pbkdf2').timeit(number=1)

        # These values are chosen as a reasonable tradeoff between time

        # to run the test suite and false positives caused by imprecise

        # measurement.

        n1, n2 = 200000, 800000

        elapsed = lambda f: timeit.Timer(f, 

                    'from django.utils.crypto import pbkdf2').timeit(number=1)

        t1 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n1)

        t2 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n2)

        measured_scale_exponent = math.log(t2 / t1, n2 / n1)

        # This should be less than 1. We allow up to 1.1 so that tests don't 

        # This should be less than 1. We allow up to 1.2 so that tests don't 

        # fail nondeterministically too often.

        self.assertLess(measured_scale_exponent, 1.1)
 
        self.assertLess(measured_scale_exponent, 1.2)