QUAD: a practical stream cipher with provable security

  • Authors:
  • Côme Berbain;Henri Gilbert;Jacques Patarin

  • Affiliations:
  • France Telecom Research and Development, Issy-les-Moulineaux, France;France Telecom Research and Development, Issy-les-Moulineaux, France;Université de Versailles, Versailles, France

  • Venue:
  • EUROCRYPT'06 Proceedings of the 24th annual international conference on The Theory and Applications of Cryptographic Techniques
  • Year:
  • 2006

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Abstract

We introduce a practical stream cipher with provable security named QUAD. The cipher relies on the iteration of a multivariate quadratic system of m equations in n m unknowns over a finite field. The security of the keystream generation of QUAD is provably reducible to the conjectured intractability of the MQ problem, namely solving a multivariate system of quadratic equations. Our recommended version of QUAD uses a 80-bit key, 80-bit IV and an internal state of n = 160 bits. It outputs 160 keystream bits (m = 320) at each iteration until 240 bits of keystream have been produced.