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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
This commit is contained in:
Paul McMillan 2012-02-02 04:44:17 +00:00
parent ccbadbc5c2
commit 1030d66a14
2 changed files with 34 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
django/utils/crypto.py
View File

@ -10,8 +10,8 @@ import operator
from django.conf import settings from django.conf import settings
trans_5c = "".join([chr(x ^ 0x5C) 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)]) _trans_36 = "".join([chr(x ^ 0x36) for x in xrange(256)])
def salted_hmac(key_salt, value, secret=None): def salted_hmac(key_salt, value, secret=None):
@ -66,7 +66,7 @@ def constant_time_compare(val1, val2):
return result == 0 return result == 0
def bin_to_long(x): def _bin_to_long(x):
""" """
Convert a binary string into a long integer Convert a binary string into a long integer
@ -75,17 +75,15 @@ def bin_to_long(x):
return long(x.encode('hex'), 16) 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) return binascii.unhexlify(hex_format_string % x)
if len(hex) % 2 == 1:
hex = '0' + hex
return binascii.unhexlify(hex)
def fast_hmac(key, msg, digest): def _fast_hmac(key, msg, digest):
""" """
A trimmed down version of Python's HMAC implementation 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: if len(key) > dig1.block_size:
key = digest(key).digest() key = digest(key).digest()
key += chr(0) * (dig1.block_size - len(key)) key += chr(0) * (dig1.block_size - len(key))
dig1.update(key.translate(trans_36)) dig1.update(key.translate(_trans_36))
dig1.update(msg) dig1.update(msg)
dig2.update(key.translate(trans_5c)) dig2.update(key.translate(_trans_5c))
dig2.update(dig1.digest()) dig2.update(dig1.digest())
return dig2 return dig2
@ -123,13 +121,15 @@ def pbkdf2(password, salt, iterations, dklen=0, digest=None):
l = -(-dklen // hlen) l = -(-dklen // hlen)
r = dklen - (l - 1) * hlen r = dklen - (l - 1) * hlen
hex_format_string = "%%0%ix" % (hlen * 2)
def F(i): def F(i):
def U(): def U():
u = salt + struct.pack('>I', i) u = salt + struct.pack('>I', i)
for j in xrange(int(iterations)): for j in xrange(int(iterations)):
u = fast_hmac(password, u, digest).digest() u = _fast_hmac(password, u, digest).digest()
yield bin_to_long(u) yield _bin_to_long(u)
return long_to_bin(reduce(operator.xor, U())) return _long_to_bin(reduce(operator.xor, U()), hex_format_string)
T = [F(x) for x in range(1, l + 1)] T = [F(x) for x in range(1, l + 1)]
return ''.join(T[:-1]) + T[-1][:r] return ''.join(T[:-1]) + T[-1][:r]

23
tests/regressiontests/utils/crypto.py
View File

@ -108,6 +108,17 @@ class TestUtilsCryptoPBKDF2(unittest.TestCase):
"c4007d5298f9033c0241d5ab69305e7b64eceeb8d" "c4007d5298f9033c0241d5ab69305e7b64eceeb8d"
"834cfec"), "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): def test_public_vectors(self):
@ -125,11 +136,15 @@ class TestUtilsCryptoPBKDF2(unittest.TestCase):
Theory: If you run with 100 iterations, it should take 100 Theory: If you run with 100 iterations, it should take 100
times as long as running with 1 iteration. times as long as running with 1 iteration.
""" """
n1, n2 = 1000, 100000 # These values are chosen as a reasonable tradeoff between time
elapsed = lambda f: timeit.Timer(f, 'from django.utils.crypto import pbkdf2').timeit(number=1) # 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) t1 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n1)
t2 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n2) t2 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n2)
measured_scale_exponent = math.log(t2 / t1, n2 / n1) 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. # fail nondeterministically too often.
self.assertLess(measured_scale_exponent, 1.1) self.assertLess(measured_scale_exponent, 1.2)