Diffusion Analysis of Message Expansion in STITCH-256 ()
Affiliation(s)
College of Information Technology, Universiti Tenaga Nasional, Kajang, Malaysia.
Cryptography Lab, MIMOS Berhad, Technology Park Malaysia, Bukit Jalil, Malaysia.
Faculty of Computer Science and Information Technology, Universiti Putra Malaysia, Seri Kembangan, Malaysia.
ABSTRACT
Cryptographic hash functions are built up from individual
components, namely pre-processing, step transformation, and final processing.
Some of the hash functions, such as SHA-256 and STITCH-256, employ non-linear
message expansion in their pre-processing stage. However, STITCH-256 was claimed
to produce high diffusion in its message expansion. In a
cryptographic algorithm, high diffusion is desirable as it helps prevent an
attacker finding collision-producing differences, which would allow one to find
collisions of the whole function without resorting to a brute force search. In
this paper, we analyzed the diffusion property of message expansion of STITCH-256 by
observing the effect of a single bit difference over the output bits, and
compare the result with that of SHA-256. We repeated the same procedure in 3
experiments of different round. The results from the experiments showed that
the minimal weight in the message expansion of STITCH-256 is very much lower than
that in the message expansion of SHA-256, i.e. message expansion of STITCH-256 produce high diffusion. Significantly, we
showed that the probability to construct differential characteristic in
the message expansion of STITCH-256 is reduced.
Share and Cite:
N. Jamil, R. Mahmod, M. Z’aba, N. Udzir and Z. Zukarnain, "Diffusion Analysis of Message Expansion in STITCH-256,"
Journal of Information Security, Vol. 4 No. 3, 2013, pp. 129-137. doi:
10.4236/jis.2013.43015.
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