This book constitutes the refereed proceedings of the 11th IMA International Conference on Cryptography and Coding, held in Cirencester, UK in December 2007. The 22 revised full papers presented together with two invited contributions were carefully reviewed and selected from 48 submissions. The papers are organized in topical sections on signatures, boolean functions, block cipher cryptanalysis, side channels, linear complexity, public key encryption, curves, and RSA implementation.