This book constitutes the refereed proceedings of the 4th International Information Security Practice and Experience Conference, ISPEC 2008, held in Sydney, Australia, in May 2008.

The 29 revised full papers were carefully reviewed and selected from 95 submissions. The papers cover a wide range of topics in mathematics, computer science and security applications, including authentication and digital signatures, privacy, encryption and hash-function algorithms, security analysis, network security, access control, security devices, pairing and elliptic curve based security practice, security computation and so forth.