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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
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commit 1030d66a14c29026efc6c8d3ad69ad2c57bf4589 1 parent ccbadbc
Paul McMillan PaulMcMillan authored
Showing with 34 additions and 19 deletions.
  1. +15 −15 django/utils/crypto.py
  2. +19 −4 tests/regressiontests/utils/crypto.py
30 django/utils/crypto.py
View
@@ -10,8 +10,8 @@
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]
23 tests/regressiontests/utils/crypto.py
View
@@ -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 @@ def test_performance_scalability(self):
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)
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