This book constitutes the thoroughly refereed post-proceedings of the 13th International Workshop on Security Protocols, held in Cambridge, UK, in April 2005.

The 24 revised full papers presented together with edited transcriptions of some of the discussions following the presentations have passed through multiple rounds of reviewing, revision, and selection. Among the topics addressed are authentication, anonymity, cryptographics and biometrics, cryptographic protocols, network security, privacy, SPKI, user-friendliness, access control, API security, costs of security, and others.