Fast Signature Generation with a Fiat-Shamir-Like Scheme. Eurocrypt ’90

We propose two improvements to the Fiat Shamir authentication and signa-ture scheme. We reduce the communication of the Fiat Shamir authentication scheme to a single round while preserving the efficiency of the scheme. This also reduces the length of Fiat Shamir signatures. Using secret keys consisting of small integers we reduce the time for signature generation by a factor 3 to 4. We propose a variation of our scheme using class groups that may be secure even if factoring large integers becomes easy.