This book constitutes the refereed proceedings of the 6th International Conference on Security and Cryptology for Networks, SCN 2008, held in Amalfi, Italy, in September 2008. The book contains one invited talk and 26 revised full papers which were carefully reviewed and selected from 71 submissions. The papers are organized in topical sections on Implementations, Protocols, Encryption, Primitives, Signatures, Hardware and Cryptanalysis, and Key Exchange.