Paper 2010/282
Pseudo-Linear Approximations for ARX Ciphers: With Application to Threefish
Kerry A. McKay and Poorvi L. Vora
Abstract
The operations addition modulo 2^n and exclusive-or have recently been combined to obtain an efficient mechanism for nonlinearity in block cipher design. In this paper, we show that ciphers using this approach may be approximated by pseudo-linear expressions relating groups of contiguous bits of the round key, round input, and round output. The bias of an approximation can be large enough for known plaintext attacks. We demonstrate an application of this concept to a reduced-round version of the Threefish block cipher, a component of the Skein entry in the secure hash function competition.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Published elsewhere. Unknown where it was published
- Keywords
- ThreefishSkeinARX cipherlinear cryptanalysis
- Contact author(s)
- kerry @ gwu edu
- History
- 2010-08-06: last of 3 revisions
- 2010-05-12: received
- See all versions
- Short URL
- https://ia.cr/2010/282
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2010/282,
author = {Kerry A. McKay and Poorvi L. Vora},
title = {Pseudo-Linear Approximations for {ARX} Ciphers: With Application to Threefish},
howpublished = {Cryptology {ePrint} Archive, Paper 2010/282},
year = {2010},
url = {https://eprint.iacr.org/2010/282}
}
