Re: A basic question about hashing

From: Mok-Kong Shen (mok-kong.shen_at_t-online.de)
Date: 09/15/04


Date: Wed, 15 Sep 2004 11:27:39 +0200


Mok-Kong Shen wrote:

    .... I have actually also a second and simpler scheme
    that employs similar methodology, which I like to mention
    here: One employs a bijective polynomial to do the same
    as a block cipher does in CBC. The process, if desired,
    could be repeated, i.e. with the last value used as IV
    for the next round, preferrably with a different polynomial.
    (The final value could also be polynomial transformed a
    last time.)

It may be mentioned that the motivation is that (1) While
a block cipher has a key and is invertible, a bijective
polynomial has no key and is (assumed to be) hard to invert,
which is what hashing would need, (2) The analogous CBC-MAC
has been shown to be of value in practice and (3) Other
appropriate block chaning modes could be employed in place
of CBC, if desired, e.g. using the sum of all previous
output-blocks (corresponding to ciphertext blocks) to chain
instead of using simply the previous output block from the
polynomial.

M. K. Shen



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