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[Patch #1618455 by Ben Maurer] Improve speed of HMAC by using str.translate() 

instead of a more general XOR that has to construct a list.

Slightly modified from Maurer's patch: the _strxor() function is no longer
necessary at all.
This commit is contained in:
Andrew M. Kuchling 2006-12-19 14:13:05 +00:00
parent e3a985fe9a
commit 8fe2d2015d
1 changed files with 4 additions and 9 deletions
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13
Lib/hmac.py
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@ -3,10 +3,8 @@
Implements the HMAC algorithm as described by RFC 2104. Implements the HMAC algorithm as described by RFC 2104.
""" """
def _strxor(s1, s2): trans_5C = "".join ([chr (x ^ 0x5C) for x in xrange(256)])
"""Utility method. XOR the two strings s1 and s2 (must have same length). trans_36 = "".join ([chr (x ^ 0x36) for x in xrange(256)])
"""
return "".join(map(lambda x, y: chr(ord(x) ^ ord(y)), s1, s2))
# The size of the digests returned by HMAC depends on the underlying # The size of the digests returned by HMAC depends on the underlying
# hashing module used. # hashing module used.
@ -50,15 +48,12 @@ class HMAC:
self.digest_size = self.inner.digest_size self.digest_size = self.inner.digest_size
blocksize = 64 blocksize = 64
ipad = "\x36" * blocksize
opad = "\x5C" * blocksize
if len(key) > blocksize: if len(key) > blocksize:
key = self.digest_cons(key).digest() key = self.digest_cons(key).digest()
key = key + chr(0) * (blocksize - len(key)) key = key + chr(0) * (blocksize - len(key))
self.outer.update(_strxor(key, opad)) self.outer.update(key.translate(trans_5C))
self.inner.update(_strxor(key, ipad)) self.inner.update(key.translate(trans_36))
if msg is not None: if msg is not None:
self.update(msg) self.update(msg)