Information and communication security must provide technological solutions to the tension between the accelerating growth of social, economical and g- ernmental demand for digitalization of information on the one hand, and on the other, the legal and ethical obligation to protect the individuals and organi- tions involved. These proceedings contain the papers accepted at the 2010 International Conference on Information and Communications Security (ICICS 2010), held in Barcelona, Spain, during December 15-17, and hosted by the Information Security Group of the Universitat Polit’ ecnica de Catalunya, UPC. ICICS2010wasthe12theventintheICICSconferenceseries,startedin1997, which brought together leading researchers and engineers involved in multiple disciplines of information and communications security, to foster the exchange of ideas in aspects including, but not limited to, authentication and authori- tion, distributed and mobile systems security, e-commerce, fraud control, int- lectual property protection, operating system security, anonymity and privacy, and trusted computing. Inresponsetothecallforpapers,135submissionswerereceivedforthisyear’s installment of the conference series. Each paper received at least three pe- reviews on the basis of its signi?cance, novelty, technical quality and relevance to this event.The highly competitive selectionprocessresultedinonly31 papers being accepted, subject to a ?nal revision before publication. ICICS 2010 was held under the sponsorshipof the Spanish governmentand a number of private companies, particularly Scytl, which we would like to thank.