Paper 2002/152

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

Jorge Nakahara Jr, Bart Preneel, and Joos Vandewalle

Abstract

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.

Note: comments are welcome !

Metadata
Available format(s)
PDF PS
Category
Secret-key cryptography
Publication info
Published elsewhere. Unknown where it was published
Keywords
cryptanalysisblock ciphers
Contact author(s)
jorge nakahara @ esat kuleuven ac be
History
2002-10-15: received
Short URL
https://ia.cr/2002/152
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2002/152,
      author = {Jorge Nakahara Jr and Bart Preneel and Joos Vandewalle},
      title = {A note on Weak Keys of PES, IDEA and some Extended Variants},
      howpublished = {Cryptology ePrint Archive, Paper 2002/152},
      year = {2002},
      note = {\url{https://eprint.iacr.org/2002/152}},
      url = {https://eprint.iacr.org/2002/152}
}
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