Paper 2008/348

Iterative Probabilistic Reconstruction of RC4 Internal States

Jovan Golic and Guglielmo Morgari

Abstract

It is shown that an improved version of a previously proposed iterative probabilistic algorithm, based on forward and backward probability recursions along a short keystream segment, is capable of reconstructing the RC4 internal states from a relatively small number of known initial permutation entries. Given a modulus $N$, it is argued that about $N/3$ and $N/10$ known entries are sufficient for success, for consecutive and specially generated entries, respectively. The complexities of the corresponding guess-and-determine attacks are analyzed and, e.g., for $N=256$, the data and time complexities are (conservatively) estimated to be around $D \approx 2^{41}$, $C \approx 2^{689}$ and $D \approx 2^{211}$, $C \approx 2^{262}$, for the two types of guessed entries considered, respectively.

Metadata
Available format(s)
PS
Category
Secret-key cryptography
Publication info
Published elsewhere. Unknown where it was published
Keywords
stream ciphersRC4iterative probabilistic cryptanalysisguess-and-determine attacks
Contact author(s)
jovan golic @ telecomitalia it
History
2008-08-11: received
Short URL
https://ia.cr/2008/348
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2008/348,
      author = {Jovan Golic and Guglielmo Morgari},
      title = {Iterative Probabilistic Reconstruction of {RC4} Internal States},
      howpublished = {Cryptology {ePrint} Archive, Paper 2008/348},
      year = {2008},
      url = {https://eprint.iacr.org/2008/348}
}
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