Abstract:

Based on the cryptanalysis of multivariate public key cryptosystems the hidden fields equations (HFE) system with some external variables (HFEv) and internal perturbation of HFE (IPHFE), a hybrid multivariate signature scheme is proposed. In this scheme, both methods of the external perturbation in HFEv and the internal perturbation in IPHFE are used, with which the existing attacks against HFEv and IPHFE become invalid. Thus the security of the proposed scheme have been enhanced, while the total amount of computation does not increase too much. Furthermore, the security of the proposed signature scheme can be improved by the method of minus, or by multiplying two perturbations to produce mutual effect.

Key words: multivariate public key cryptography, digital signature, hidden fields equations, the HFE system with some external variables, internal perturbation of HFE