This book constitutes the strictly refereed post-workshop proceedings of the First International Workshop on Information Security, ISW'98, h eld in Tatsunokuchi, Ishikawa, Japan, in September 1997. The volume pr esents six invited surveys together with 25 thoroughly revised full pa pers selected from 39 submissions. Among the topics covered are public -key cryptosystems, cryptoanalysis, digital signatures, hardware/softw are implementation, key management, key sharing, security management, electronic commerce, and quantum cryptology.