Paper 2001/106
Cryptanalysis of the COS (2,128) Stream Ciphers
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. COS(2,128) Mode I and COS(2,128) Mode II are particular members of this family for which the authors proposed a cryptanalysis challenge. The ciphers accept secret keys of 256, 192 or 128 bits. In this note we cryptanalyse both of these ciphers, using a small amount of known keystream — with negligible effort in the case of Mode II, and with effort well below that required for a single DES key search in the case of Mode I.
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
- 2001-12-11: received
- Short URL
- https://ia.cr/2001/106
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2001/106,
author = {Steve Babbage},
title = {Cryptanalysis of the {COS} (2,128) Stream Ciphers},
howpublished = {Cryptology {ePrint} Archive, Paper 2001/106},
year = {2001},
url = {https://eprint.iacr.org/2001/106}
}
