On the security of the Courtois-Finiasz-Sendrier signature

Abstract

Abstract We prove that a variant of the Courtois-Finiasz-Sendrier signature is strongly existentially unforgeable under chosen message attack in the random oracle model, assuming hardness of the Permuted Goppa Syndrome Decoding Problem (also known as the Niederreiter problem). In addition, we explicitly show that security against key substitution attacks can be arranged by a standard technique of Menezes and Smart, hashing the public key.