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Fixed #21253 -- PBKDF2 with cached HMAC key 

This gives a 2x speed increase compared to the existing implementation.

Thanks to Steve Thomas for the initial patch and Tim Graham for finishing it.
This commit is contained in:
Florian Apolloner 2013-09-17 18:14:38 -05:00
parent 1e39982b6e
commit 1e4f53a6eb
1 changed files with 9 additions and 20 deletions
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29
django/utils/crypto.py
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@ -116,22 +116,6 @@ def _long_to_bin(x, hex_format_string):
return binascii.unhexlify((hex_format_string % x).encode('ascii')) return binascii.unhexlify((hex_format_string % x).encode('ascii'))
def _fast_hmac(key, msg, digest):
"""
A trimmed down version of Python's HMAC implementation.
This function operates on bytes.
"""
dig1, dig2 = digest(), digest()
if len(key) != dig1.block_size:
raise ValueError('Key size needs to match the block_size of the digest.')
dig1.update(key.translate(hmac.trans_36))
dig1.update(msg)
dig2.update(key.translate(hmac.trans_5C))
dig2.update(dig1.digest())
return dig2
def pbkdf2(password, salt, iterations, dklen=0, digest=None): def pbkdf2(password, salt, iterations, dklen=0, digest=None):
""" """
Implements PBKDF2 as defined in RFC 2898, section 5.2 Implements PBKDF2 as defined in RFC 2898, section 5.2
@ -160,16 +144,21 @@ def pbkdf2(password, salt, iterations, dklen=0, digest=None):
hex_format_string = "%%0%ix" % (hlen * 2) hex_format_string = "%%0%ix" % (hlen * 2)
inner_digest_size = digest().block_size inner, outer = digest(), digest()
if len(password) > inner_digest_size: if len(password) > inner.block_size:
password = digest(password).digest() password = digest(password).digest()
password += b'\x00' * (inner_digest_size - len(password)) password += b'\x00' * (inner.block_size - len(password))
inner.update(password.translate(hmac.trans_36))
outer.update(password.translate(hmac.trans_5C))
def F(i): def F(i):
def U(): def U():
u = salt + struct.pack(b'>I', i) u = salt + struct.pack(b'>I', i)
for j in xrange(int(iterations)): for j in xrange(int(iterations)):
u = _fast_hmac(password, u, digest).digest() dig1, dig2 = inner.copy(), outer.copy()
dig1.update(u)
dig2.update(dig1.digest())
u = dig2.digest()
yield _bin_to_long(u) yield _bin_to_long(u)
return _long_to_bin(reduce(operator.xor, U()), hex_format_string) return _long_to_bin(reduce(operator.xor, U()), hex_format_string)