A Cryptanalysis of the Double-Round Quadratic Cryptosystem

In the 80’s Matsumoto and Imai [8] proposed public key cryptosystems based on the difficulty of solving systems of polynomials in several variables. Although these first schemes were broken, many others followed, leading to a very active field known as Multivariate cryptography. In this paper, we show how to break one of these schemes, the Double-Round Quadratic cryptosystem from [12]. We stress that this cryptosystem has, in practice, already been cryptanalysed in [5]. However their attack uses several “non-standard” heuristics, they provide experimental evidence, but no proof is given, as opposed to this present article. Our attack uses a very general technique introduced in [9] to break the cryptosystem.

• Type: Conference
• Year: 2007
• Where: ICISC
• Authors: Antoine Scemama
• Keywords: Cryptology, Cryptosystem, Double-Round Quadratic Cryptosystem, ICISC 2007, Public Key Cryptosystems