Commit 1e4f53a6 authored by Florian Apolloner's avatar Florian Apolloner
Browse files

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.
parent 1e39982b

django/utils/crypto.py

+9 −20
Original line number Diff line number Diff line
@@ -116,22 +116,6 @@ def _long_to_bin(x, hex_format_string): 
    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):

    """

    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)



    inner_digest_size = digest().block_size

    if len(password) > inner_digest_size:

    inner, outer = digest(), digest()

    if len(password) > inner.block_size:

        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 U():

            u = salt + struct.pack(b'>I', i)

            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)

        return _long_to_bin(reduce(operator.xor, U()), hex_format_string)