The book includes 17 revised full papers, 1 system presentation paper and the transcriptions of 5 panel sessions from FC 2007. The papers, which were carefully reviewed and selected from 85 submissions, are organized in topical sections on Payment Systems, Anonymity, Authentication, Anonymity and Privacy, Cryptography and Commercial Transactions, Financial Transactions and Web Services, and Cryptography. The book concludes with 5 revised full and 5 revised short papers from the USEC 2007 workshop. This workshop brought together an interdisciplinary group of researchers and practitioners to discuss usability problems and deepen the understanding of users' capabilities and motivations in performing security tasks.