Mycrypt 2005 was the inaugural international conference on cryptology hosted in Malaysia. The conference was co-organized by the Information Security - search Lab at Swinburne University of Technology (Sarawak Campus), NISER (National ICT Security and Emergency Response Centre) and INSPEM (Ins- tute for MathematicalResearch)at UPM (UniversityPutra Malaysia).Mycrypt 2005 was held in Kuala Lumpur, Malaysia during September 28-30 2005, in conjunction with the e-Secure Malaysia 2005 convention. Therewere90paper submissionsfrom23 countriescoveringall areasof cr- tologic research, from which 19 were accepted. We would like to extend our thanks to all authors who submitted papers to Mycrypt 2005. Each paper was sentanonymouslytoatleast3membersoftheInternationalProgramCommittee for reviews and comments. The review comments were then followed by disc- sions among the Program Committee. A recipient of the Best Paper Award was also selected after voting among Program Committee members. The winning paper was "Distinguishing Attacks on T-functions" by Simon Kunzli .. (FH A- gau, Swizerland), Pascal Junod (Nagravision SA, Switzerland) and Willi Meier (FH Aargau, Swizerland). These proceedings contain revised versions of all the accepted papers. The conference program included three keynote papers: Hideki Imai (Tokyo University)presenteda paper entitled "TrendsandChallenges forSecurer Cr- tography in Practice". Moti Yung (Columbia University) presented a paper entitled "E?cient Secure Group Signatures with Dynamic Joins and Keeping Anonymity Against Group Managers". Colin Boyd (QUT) presented a paper entitled "Security of Two-Party Identity-Based Key Agreement". We are extremely grateful for the time and e?ort of all the members of the Program Committee in the review process. Their names may be found overleaf.