Paper 2006/010

Finding Characteristic Polynomials with Jump Indices

Steve Babbage and Matthew Dodd


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.

Note: More complete references, plus one typo correction

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Publication info
Published elsewhere. Unknown where it was published
MICKEYstream cipherECRYPTirregular clocking
Contact author(s)
steve babbage @ vodafone com
2006-01-13: revised
2006-01-10: received
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      author = {Steve Babbage and Matthew Dodd},
      title = {Finding Characteristic Polynomials with Jump Indices},
      howpublished = {Cryptology ePrint Archive, Paper 2006/010},
      year = {2006},
      note = {\url{}},
      url = {}
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