Cryptanalysis of a public key encryption scheme based on QC-LDPC and QC-MDPC codes

摘要

This letter presents a cryptanalysis of the modified McEliece cryptosystemrecently proposed by Moufek, Guenda and Gulliver [24]. The system is based onthe juxtaposition of quasi-cyclic LDPC and quasi-cyclic MDPC codes. The idea ofour attack is to find an alternative permutation matrix together with anequivalent LDPC code which allow the decoding of any cipher-text with a veryhigh probability. We also apply a recent technique to determine weak keys [4]for this scheme. The results show that the probability of weak keys is highenough that this variant can be ruled out as a possible secure encryptionscheme.