World Library  
Flag as Inappropriate
Email this Article

Loki97

Article Id: WHEBN0000611984
Reproduction Date:

Title: Loki97  
Author: World Heritage Encyclopedia
Language: English
Subject: WikiProject Cryptography, Advanced Encryption Standard process, LOKI, Lawrie Brown, Josef Pieprzyk
Collection: Broken Block Ciphers, Feistel Ciphers
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Loki97

LOKI97
The LOKI97 round function
General
Designers Lawrie Brown, assisted by Jennifer Seberry and Josef Pieprzyk
First published 1998
Derived from LOKI91
Cipher detail
Key sizes 128, 192 or 256 bits
Block sizes 128 bits
Structure Feistel network
Rounds 16
Best public cryptanalysis
Linear cryptanalysis against LOKI97, requiring 256 known plaintexts (Knudsen and Rijmen, 1999).

In cryptography, LOKI97 is a block cipher which was a candidate in the Advanced Encryption Standard competition. It is a member of the LOKI family of ciphers, earlier instances being LOKI89 and LOKI91. LOKI97 was designed by Lawrie Brown, assisted by Jennifer Seberry and Josef Pieprzyk.

Like DES, LOKI97 is a 16-round Feistel cipher, and like other AES candidates, has a 128-bit block size and a choice of a 128-, 192- or 256-bit key length. It uses 16 rounds of a balanced feistel network to process the input data blocks (see diagram right). The complex round function f incorporates two substitution-permutation layers in each round.The key schedule is also a Feistel structure — an unbalanced one unlike the main network — but using the same F-function.

Overall LOKI97 Cipher Structure

The LOKI97 round function (shown right) uses two columns each with multiple copies of two basic S-boxes. These S-boxes are designed to be highly non-linear and have a good XOR profile. The permutations before and between server to provide auto-keying and to diffuse the S-box outputs as quickly as possible.

The authors have stated that, "LOKI97 is a non-proprietary algorithm, available for royalty-free use worldwide as a possible replacement for the DES or other existing block ciphers." It was intended to be an evolution of the earlier LOKI89 and LOKI91 block ciphers.

It was the first published candidate in the Advanced Encryption Standard competition, and was quickly analysed and attacked. An analysis of some problems with the LOKI97 design, which led to its rejection when shortlisting candidates, is given in the paper (Rijmen & Knudsen 1999). It was found to be susceptible to an effective theoretical differential cryptanalysis attack considerably faster than an exhaustive search.

See also

References

  • L. Brown, J. Pieprzyk: Introducing the new LOKI97 Block Cipher
  • L.R. Knudsen and V. Rijmen, "Weaknesses in LOKI97", Proceedings of the 2nd AES Candidate Conference, Rome, March 22–23, 1999, pp. 168–174.
  • Wenling Wu, Bao Li, Denguo Feng, Sihan Qing, "Cryptanalysis of some AES candidate algorithms", Information and Communication Security - ICICS'99, LNCS 1726, pp 13–21, V Varadharajan (ed), Springer-Verlag 1999.
  • Wenling Wu, Bao Li, Denguo Feng, Sihan Qing, "Linear cryptanalysis of LOKI97", Journal of Software, vol 11 no 2, pp 202–6, Feb 2000.

External links

  • The LOKI97 homepage
  • The design of LOKI97
  • SCAN's entry for LOKI97
  • John Savard's Description of LOKI97
  • Online-implementation of LOKI97 at serversniff.net
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.