Rudolph, C.C.RudolphGürgens, S.S.Gürgens2022-03-032022-03-032005https://publica.fraunhofer.de/handle/publica/20907610.1007/s00165-004-0055-4An approach to protocol analysis using asynchronous product automata (APA) and the simple homomorphism verification tool (SHVT) is demonstrated on several variants of the well known Zhou-Gollmann fair non-repudiation protocol and on two more recent optimistic fair non-repudiation protocols. Attacks on all these protocols are presented and an improved version of the Zhou-Gollmann protocol is proposed.en005004journal article