This book constitutes the refereed proceedings of the First International Conference on Provable Security, ProvSec 2007, held in Wollongong, Australia. The 10 revised full papers presented together with seven short papers were carefully reviewed and selected. The papers are organized in topical sections on Authentication, Asymmetric Encryption, Signature, Protocol and Proving Technique, Authentication and Symmetric Encryption, Signature and Asymmetric Encryption.