How to Construct Super-Pseudorandom Permutations with Short Keys*A preliminary version of this paper appears in [8].

  • Authors:

  • Tetsu Iwata;Kaoru Kurosawa

  • Affiliations:

  • The author is with the Dept. of Computational Science and Engineering, Nagoya University, Nagoya-shi, 464-8603 Japan. E-mail: iwata@cse.nagoya-u.ac.jp,;The author is with the Dept. of Computer and Information Sciences, Ibaraki University, Hitachi-shi, 316-8511 Japan. E-mail: kurosawa@mx.ibaraki.ac.jp

  • Venue:
  • IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
  • Year:
  • 2007

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Abstract

It is known that a super-pseudorandom permutation can be constructed from a pseudorandom function f and two universal hash functions, h and h'. It is a four round Feistel permutation denoted by ψ(hk, f, f, h'k'). In this paper, we show how to re-use the secret key for f in this construction. Specifically, we show that (1) the same key can be used for both h and h', and (2) the key for h and h' can be derived from f. As a result, our construction requires only the key for f as a secret key, and it preserves computational efficiency and security. We show the full security proof of our construction. Also, we derive a similar result for a five round MISTY-type permutation.