Paper Abstract and Keywords |
Presentation |
2009-07-03 10:45
On the strength evaluation of Lesamnta against differential cryptanalysis Yasutaka Igarashi, Toshinobu Kaneko (Tokyo Univ. of Science) ISEC2009-28 SITE2009-20 ICSS2009-42 |
Abstract |
(in Japanese) |
(See Japanese page) |
(in English) |
We focus on the cryptographic hash algorithm Lesamnta-256, which is one of the
candidates for the new hash algorithm SHA-3. Lesamnta-256 consists of
the Merkle-Damg\r{a}rd iteration of a compression function. The
compression function consists of
a mixing function and a key scheduling function. The mixing function
consists of the 32 rounds of the four-way generalized Feistel structure.
There is a nonlinear function $F$ with 64-bit input/output on each
round, which consists of the 4 steps of AES type of SPN structure. A subkey
is XORed only at the first step of SPN. We analyze the security of
these components of Lesamnta as is,
although the designers analyzed its security by assuming that the subkey is
XORed at every step of SPN. We show that the 2 steps of SPN referred to
as XS have the maximum differential probability $2^{-11.415}$.
This probability is greater than both of the differential characteristic
probability $2^{-18}$ and the differential probability $2^{-12}$
derived under the independent subkey assumption. On the strength of
whole compression function, we show that there are at
least 15 active $F$ functions in the mixing function. As the input bit
width of the mixing function is 256, we can say that it is secure against differential attack if the maximum differential probability of $F$ function is less than
$2^{-256/15}$ = $2^{-17.067}$.
Finally we show that the key scheduling function is
secure against differential cryptanalysis. |
Keyword |
(in Japanese) |
(See Japanese page) |
(in English) |
Lesamnta / differential cryptanalysis / higher-order differential / SHA-3 / hash function / / / |
Reference Info. |
IEICE Tech. Rep., vol. 109, no. 113, ISEC2009-28, pp. 147-152, July 2009. |
Paper # |
ISEC2009-28 |
Date of Issue |
2009-06-25 (ISEC, SITE, ICSS) |
ISSN |
Print edition: ISSN 0913-5685 Online edition: ISSN 2432-6380 |
Copyright and reproduction |
All rights are reserved and no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Notwithstanding, instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. (License No.: 10GA0019/12GB0052/13GB0056/17GB0034/18GB0034) |
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ISEC2009-28 SITE2009-20 ICSS2009-42 |
Conference Information |
Committee |
ISEC IPSJ-CSEC SITE ICSS |
Conference Date |
2009-07-02 - 2009-07-03 |
Place (in Japanese) |
(See Japanese page) |
Place (in English) |
Akita University |
Topics (in Japanese) |
(See Japanese page) |
Topics (in English) |
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Paper Information |
Registration To |
ISEC |
Conference Code |
2009-07-ISEC-CSEC-SITE-ICSS |
Language |
Japanese |
Title (in Japanese) |
(See Japanese page) |
Sub Title (in Japanese) |
(See Japanese page) |
Title (in English) |
On the strength evaluation of Lesamnta against differential cryptanalysis |
Sub Title (in English) |
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Keyword(1) |
Lesamnta |
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differential cryptanalysis |
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higher-order differential |
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SHA-3 |
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hash function |
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1st Author's Name |
Yasutaka Igarashi |
1st Author's Affiliation |
Tokyo University of Science (Tokyo Univ. of Science) |
2nd Author's Name |
Toshinobu Kaneko |
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Tokyo University of Science (Tokyo Univ. of Science) |
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Speaker |
Author-1 |
Date Time |
2009-07-03 10:45:00 |
Presentation Time |
25 minutes |
Registration for |
ISEC |
Paper # |
ISEC2009-28, SITE2009-20, ICSS2009-42 |
Volume (vol) |
vol.109 |
Number (no) |
no.113(ISEC), no.114(SITE), no.115(ICSS) |
Page |
pp.147-152 |
#Pages |
6 |
Date of Issue |
2009-06-25 (ISEC, SITE, ICSS) |
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