Book excerpt: This book constitutes the refereed proceedings of the 9th International Conference on Information Security and Cryptology, ICISC 2006, held in Busan, Korea in November/December 2006. The 26 revised full papers presented together with two invited talks have gone through two rounds of reviewing and improvement and were selected from 129 submissions. The papers are organized in topical sections on hash functions, block and stream ciphers, efficient implementation and hardware, network security and access control, mobile communications security, forensics, copyright protection, biometrics, public key cryptosystems, and digital signatures.