Paper 2001/078

The COS Stream Ciphers are Extremely Weak

Steve Babbage

Abstract

A new family of very fast stream ciphers called COS (for "crossing over system") has been proposed by Filiol and Fontaine, and seems to have been adopted for at least one commercial standard. In this note we show that the COS ciphers are very weak indeed — it requires negligible effort to reconstruct the state of the keystream generator from a very small amount of known keystream.

Metadata
Available format(s)
PDF PS
Category
Secret-key cryptography
Publication info
Published elsewhere. Unknown where it was published
Keywords
COSstream ciphernonlinear feedback shift registercryptanalysis
Contact author(s)
steve babbage @ vodafone com
History
2001-09-11: received
Short URL
https://ia.cr/2001/078
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2001/078,
      author = {Steve Babbage},
      title = {The COS Stream Ciphers are Extremely Weak},
      howpublished = {Cryptology ePrint Archive, Paper 2001/078},
      year = {2001},
      note = {\url{https://eprint.iacr.org/2001/078}},
      url = {https://eprint.iacr.org/2001/078}
}
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