Paper 2010/593
Differential Attack on Five Rounds of the SC2000 Block Cipher
Jiqiang Lu
Abstract
The SC2000 block cipher has a 128-bit block size and a user key of 128, 192 or 256 bits, which employs a total of 6.5 rounds if a 128-bit user key is used. It is a CRYPTREC recommended e-government cipher. In this paper we describe two 4.75-round differential characteristics with probability $2^{-126}$ of SC2000 and seventy-six 4.75-round differential characteristics with probability $2^{-127}$. Finally, we present a differential cryptanalysis attack on a 5-round reduced version of SC2000 when used with a 128-bit key; the attack requires $2^{125.68}$ chosen plaintexts and has a time complexity of $2^{125.75}$ 5-round SC2000 encryptions. It suggests for the first time that the safety margin of SC2000 with a 128-bit key decreases below one and a half rounds.
Note: In this enhanced version, we address how to recover the user key from a few subkey bits of SC2000, give more non-trivial 4.75-round differential characteristics, and present a more efficient attack.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Published elsewhere. A preliminary version of this work was presented at Inscrypt 2009.
- Keywords
- Block cipherSC2000Differential cryptanalysis
- Contact author(s)
- lvjiqiang @ hotmail com
- History
- 2010-12-04: revised
- 2010-11-23: received
- See all versions
- Short URL
- https://ia.cr/2010/593
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2010/593,
author = {Jiqiang Lu},
title = {Differential Attack on Five Rounds of the {SC2000} Block Cipher},
howpublished = {Cryptology {ePrint} Archive, Paper 2010/593},
year = {2010},
url = {https://eprint.iacr.org/2010/593}
}