International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Finding Characteristic Polynomials with Jump Indices

Steve Babbage
Matthew Dodd
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Abstract: Jansen introduced a technique for building LFSRs that can be clocked a large number of times with a single simple operation. These may be useful in the construction of stream ciphers based on clock-controlled LFSRs. However, for LFSR sizes of typical interest, it appears generally hard to find such jumping LFSRs with particular desired parameters. In this note we explain a trick which we used to find the jumping LFSRs in MICKEY and MICKEY-128, and which may be useful for future applications.
  title={Finding Characteristic Polynomials with Jump Indices},
  booktitle={IACR Eprint archive},
  keywords={MICKEY, stream cipher, ECRYPT, irregular clocking},
  note={ 13161 received 9 Jan 2006, last revised 13 Jan 2006},
  author={Steve Babbage and Matthew Dodd},