This book constitutes the thoroughly refereed proceedings of the 11th International Conference on Financial Cryptography and Data Security, FC 2007, and the co-located 1st International Workshop on Usable Security, USEC 2007, both held in Scarborough, Trinidad/Tobago, in February 2007.

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.