Description of a new variable-length key, 64-bit block cipher (Blowfish)

  • Bruce Schneier
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 809)


Blowfish, a new secret-key block cipher, is proposed. It is a Feistel network, iterating a simple encryption function 16 times. The block size is 64 bits, and the key can be any length up to 448 bits. Although there is a complex initialization phase required before any encryption can take place, the actual encryption of data is very efficient on large microprocessors.


Encryption Algorithm Block Cipher Data Encryption Standard Linear Cryptanalysis Differential Cryptanalysis 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    E. Biham and A. Shamir, Differential Cryptanalysis of the Data Encryption Standard, Springer-Verlag, 1993.Google Scholar
  2. 2.
    T.W. Cusick and M.C. Wood, “The REDOC-II Cryptosystem,“ Advances in Cryptology-CRYPTO '90 Proceedings, Springer-Verlag, 1991, pp. 545–563.Google Scholar
  3. 3.
    J. Deamen, R. Govaerts, and J. Vandewalle, “Block Ciphers Based on Modular Arithmetic,” Proceedings of the 3rd Symposium on State and Progress of Research in Cryptography, Rome, Italy, 15–16 Feb 1993, pp. 80–89.Google Scholar
  4. 4.
    J.-H. Evertse, “Linear Structures in Blockciphers,” Advances in Cryptology-EUROCRPYT '87, Springer-Verlag, 1988, pp. 249–266.Google Scholar
  5. 5.
    H. Feistel, “Cryptography and Computer Privacy,” Scientific American, v. 228, n. 5, May 73, pp. 15–23.Google Scholar
  6. 6.
    GOST 28147-89, “Cryptographic Protection for Data Processing Systems,” “Cryptographic Transformation Algorithm,” Government Standard of the U.S.S.R., Inv. No. 3583, UDC 681.325.6:006.354. (in Russian)Google Scholar
  7. 7.
    X. Lai, J. Massey, and S. Murphy, “Markov Ciphers and Differential Cryptanalysis,” Advances in Cryptology-EUROCRYPT '91 Proceedings, Springer-Verlag, 1991, pp. 17–38.Google Scholar
  8. 8.
    J.L. Massey and X. Lai, “Device for Converting a Digital Block and the Use Thereof,” International Patent PCT/CH91/00117, 16 May 1991.Google Scholar
  9. 9.
    J.L. Massey and X. Lai, “Device for the Conversion of a Digital Block and Use of Same,” U.S. Patent 5,214,703, 25 May 1993.Google Scholar
  10. 10.
    M. Matsui, “Linear Cryptanalysis Method for DES Cipher,” Advances in Cryptology-CRYPTO '93 Proceedings, Springer-Verlag, 1994, in preparation.Google Scholar
  11. 11.
    R.C. Merkle, “Fast Software Encryption Functions,” Advances in Cryptology-CRYPTO '90 Proceedings, Springer-Verlag, 1991, pp. 476–501.Google Scholar
  12. 12.
    R.C. Merkle, “Method and Apparatus for Data Encryption,” U.S. Patent 5,003,597, 26 Mar 1991.Google Scholar
  13. 13.
    S. Miyaguchi, “The FEAL-8 Cryptosystem and Call for Attack,” Advances in Cryptology-CRYPTO '89 Proceedings, Springer-Verlag, 1990, pp. 624–627.Google Scholar
  14. 14.
    S. Miyaguchi, “Expansion of the FEAL Cipher,” NTT Review, v. 2, n. 6, Nov 1990.Google Scholar
  15. 15.
    S. Miyaguchi, “The FEAL Cipher Family,” Advances in Cryptology-CRYPTO '90 Proceedings, Springer-Verlag, 1991, pp. 627–638.Google Scholar
  16. 16.
    National Bureau of Standards, Data Encryption Standard, U.S. Department of Commerce, FIPS Publication 46, Jan 1977.Google Scholar
  17. 17.
    National Institute of Standards and Technology, “Clipper Chip Technology,” 30 Apr 1993.Google Scholar
  18. 18.
    RSA Laboratories, Answers to Frequently Asked Questions About Today's Cryptography, Revision 2.0, RSA Data Security Inc., 5 Oct 1993.Google Scholar
  19. 19.
    B. Schneier, “Data Guardians,” MacWorld, Feb 1993, 145–151.Google Scholar
  20. 20.
    B. Schneier, Applied Cryptography, John Wiley & Sons, New York, 1994.Google Scholar
  21. 21.
    J.L Smith, The Design of Lucifer, A Cryptographic Device for Data Communication, RC 3326, White Plains: IBM Research.Google Scholar
  22. 22.
    M.J. Weiner, “Efficient DES Key Search,” Advances in Cryptology-CRYPTO '93 Proceedings, Springer-Verlag, in preparation.Google Scholar
  23. 23.
    M.C. Wood, “Method of Cryptographically Transforming Electronic Digital Data from One Form to Another,” U.S. Patent 5,003,596, 26 Mar 1991.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1994

Authors and Affiliations

  • Bruce Schneier
    • 1
  1. 1.Counterpane SystemsOak Park

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