On Lai-Massey and quasi-Feistel ciphers

Aaram Yun, Je Hong Park, Jooyoung Lee

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


We introduce a new notion called a quasi-Feistel cipher, which is a generalization of the Feistel cipher, and contains the Lai-Massey cipher as an instance. We show that most of the works on the Feistel cipher can be naturally extended to the quasi-Feistel cipher. From this, we give a new proof for Vaudenay's theorems on the security of the Lai-Massey cipher, and also we introduce for Lai-Massey a new construction of pseudorandom permutation, analoguous to the construction of Naor-Reingold using pairwise independent permutations. Also, we prove the birthday security of (2b-1)- and (3b-2)-round unbalanced quasi-Feistel ciphers with b branches against CPA and CPCA attacks, respectively.

Original languageEnglish
Pages (from-to)45-72
Number of pages28
JournalDesigns, Codes, and Cryptography
Issue number1
StatePublished - Jan 2011


  • Block cipher design
  • Feistel cipher
  • Indistinguishability
  • Lai-Massey cipher
  • Luby-Rackoff
  • Pseudorandom function


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