CRYPTOGRAPHIC MESSAGE SIGNATURE METHOD HAVING STRENGTHENED SECURITY, SIGNATURE VERIFICATION METHOD, AND CORRESPONDING DEVICES AND COMPUTER PROGRAM PRODUCTS

摘要

A cryptographic message signature method are provided, which have strengthened security. The method implements two sets of signature algorithms SA1={K1, S1, V1} and SA2={K2, S2, V2}, where Ki, Si and Vi are key generation algorithms, signature generation algorithms and signature verification algorithms, respectively. The method includes: a step of generating permanent keys using the algorithm K1, delivering a pair of private and public keys {sk1, pk1}; and, for at least one message m to be signed: a signature step including sub-steps. The sub-steps include: receipt of the message m to be signed; generation of an ephemeral key pair {sk2,pk2} using the algorithm K2; calculation, by the signature algorithm S2, of the signature s2 of the message m by the private key sk2; calculation, by the signature algorithm S1, of the signature c1 of the public key pk2 by the private key sk1; and providing the strengthened signature {s2, c1, pk2}.