This book constitutes the refereed proceedings of the 7th IMA Conference on Cryptography and Coding held in Cirencester, UK, in December 1999. The 35 revised full papers presented were carefully reviewed and selected for inclusion in the proceedings. Among the topics covered are error-correcting coding, arithmetic coding for data compression and encryption, image coding, biometric authentication, broadcast channel access, graph and trellis decoding, turbo codes, convolution codes, Reed Solomon codes, elliptic curve cryptography, primality testing, finite-field arithmetic, and cryptographic protocols.