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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.
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@ -116,22 +116,6 @@ def _long_to_bin(x, hex_format_string):
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return binascii.unhexlify((hex_format_string % x).encode('ascii'))
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def _fast_hmac(key, msg, digest):
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"""
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A trimmed down version of Python's HMAC implementation.
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This function operates on bytes.
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"""
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dig1, dig2 = digest(), digest()
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if len(key) != dig1.block_size:
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raise ValueError('Key size needs to match the block_size of the digest.')
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dig1.update(key.translate(hmac.trans_36))
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dig1.update(msg)
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dig2.update(key.translate(hmac.trans_5C))
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dig2.update(dig1.digest())
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return dig2
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def pbkdf2(password, salt, iterations, dklen=0, digest=None):
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"""
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Implements PBKDF2 as defined in RFC 2898, section 5.2
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@ -160,16 +144,21 @@ def pbkdf2(password, salt, iterations, dklen=0, digest=None):
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hex_format_string = "%%0%ix" % (hlen * 2)
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inner_digest_size = digest().block_size
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if len(password) > inner_digest_size:
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inner, outer = digest(), digest()
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if len(password) > inner.block_size:
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password = digest(password).digest()
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password += b'\x00' * (inner_digest_size - len(password))
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password += b'\x00' * (inner.block_size - len(password))
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inner.update(password.translate(hmac.trans_36))
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outer.update(password.translate(hmac.trans_5C))
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def F(i):
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def U():
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u = salt + struct.pack(b'>I', i)
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for j in xrange(int(iterations)):
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u = _fast_hmac(password, u, digest).digest()
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dig1, dig2 = inner.copy(), outer.copy()
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dig1.update(u)
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dig2.update(dig1.digest())
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u = dig2.digest()
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yield _bin_to_long(u)
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return _long_to_bin(reduce(operator.xor, U()), hex_format_string)
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