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Published in:
2006 | OriginalPaper | Chapter
QUAD: A Practical Stream Cipher with Provable Security
Authors : Côme Berbain, Henri Gilbert, Jacques Patarin
Published in: Advances in Cryptology - EUROCRYPT 2006
Publisher: Springer Berlin Heidelberg
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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 2
40
bits of keystream have been produced.