## CryptoDB

### Paper: A note on Weak Keys of PES, IDEA and some Extended Variants

Authors: Jorge Nakahara Jr Bart Preneel Joos Vandewalle URL: http://eprint.iacr.org/2002/152 Search ePrint Search Google This paper presents an analysis of the PES cipher in a similar setting as done by Daemen et al. at Crypto'93 for IDEA. The following results were obtained for 8.5 round PES: a linear weak-key class of size $2^{48}$; two distinct differential weak-key classes of size $2^{41}$; two differential-linear weak-key classes of size $2^{62}$. For 17-round PES (double-PES): a linear weak-key class of size $2^7$, and a differential weak-key class of size $2^7$ were found. Daemen suggested a modified key schedule for IDEA in order to avoid weak keys. We found a differential weak-key class of size $2^{83}$ for 2.5-round IDEA under his redesigned key schedule, and differential-linear relations for 3.5-round IDEA.
##### BibTeX
@misc{eprint-2002-11675,
title={A note on Weak Keys of PES, IDEA and some Extended Variants},
booktitle={IACR Eprint archive},
keywords={secret-key cryptography / cryptanalysis, block ciphers},
url={http://eprint.iacr.org/2002/152},
note={ jorge.nakahara@esat.kuleuven.ac.be 11967 received 7 Oct 2002},
author={Jorge Nakahara Jr and Bart Preneel and Joos Vandewalle},
year=2002
}