This book constitutes the refereed proceedings of the 5th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT'99, held in Singapore in November 1999. The 31 revised full papers presented together with one invited paper were carefully reviewed and selected from a total of 96 submissions. The book is divided in topical sections on assymetric key cryptosystems, cryptanalysis, elliptic curve cryptosystems, public key cryptosystems, integers and computation, network security, random numbers, key management, and authentication.