[Annotatie]: This book constitutes the refereed proceedings of the 11th International Conference on Information Security Conference, ISC 2008, held in Taipei, Taiwan, September 15-18, 2008. The 33 revised full papers presented were carefully reviewed and selected from 134 submissions. The papers are organized in topical sections on trusted computing, database and system security, intrusion detection, network security, cryptanalysis, digital signatures, AES, symmetric cryptography and hash functions, authentication as well as security protocols. [Flaptekst]: paperwasanonymouslyreviewedbyatleastthreecommitteemembers.Inorderto encourageandpromotestudentparticipation,theISC2008ProgramCommittee selected three student-coauthored papers for the Best Student Paper award,one fromeachregion:Asia,Europe,andtheAmericas.Thepaperswere,respectively,""""Deterministic Constructions of 21-Step Collisions for the SHA-2 Hash Family,"""" bySomitraSanadhyaandPalashSarkar(IndianStatisticalInstitute,India),""""C- lisions for RC4-Hash,"""" by Sebastiaan Indesteege and Bart Preneel (Katholieke UniversiteitLeuven,Belgium),and""""ProxyRe-signaturesintheStandardModel,"""" byShermanS.M. Chow(New YorkUniversity,USA) andRaphaelPhan(Lou- borough University, UK). The program also included invited speeches by Doug Tygar(UC Berkeley,USA) andTatsuakiOkamoto(NTT, Japan). Many people helped to make ISC 2008 successful. We would like to thank all thosewhocontributedtothetechnicalprogramandtoorganizingtheconference.