The FISH (FIbonacci SHrinking) stream cipher is a fast software based stream cipher using Lagged Fibonacci generators, plus a concept from the shrinking generator cipher. It was published by Siemens in 1993. FISH is quite fast in software and has a huge key length. However, in the same paper where he proposed Pike, Ross Anderson showed that FISH can be broken with just a few thousand bits of known plaintext.

  • Blöcher, Uwe; Dichtl, Markus (1994), "Fish: A fast software stream cipher", Fast Software Encryption, Lecture Notes in Computer Science, vol. 809, Springer-Verlag, pp. 41–44, doi:, ISBN 978-3-540-58108-6.
  • Anderson, Ross J. (1995), "On Fibonacci keystream generators", Fast Software Encryption, Lecture Notes in Computer Science, vol. 1008, Springer-Verlag, pp. 346–352, doi:, ISBN 978-3-540-60590-4.