This volume contains the proceedings of the 12th Financial Cryptography and DataSecurityInternationalConference,heldinCozumel,Mexico,January28-31 2008. Financial cryptography (FC) and data security has been for years the main international forum for research,advanced development, education, exploration, and debate regarding information assurance in the context of ?nance and commerce. Despite the strong competition from other top-tier related security conf- ences, the Program Committee received a signi?cant number of submissions, indicating a growingacceptance of FC as the premier ?nancialand data security forum. The ProgramCommittee, led by the PCChair Gene Tsudik, achievedan excellent program balance between research, practice, and panel sessions. T...