The ninth in the series of IMA Conferences on Cryptography and Coding was held (as ever) at the Royal Agricultural College, Cirencester, from 16-18 Dec- ber 2003. The conference’s varied programme of 4 invited and 25 contributed papers is represented in this volume. The contributed papers were selected from the 49 submissions using a – reful refereeing process. The contributed and invited papers are grouped into 5 topics: coding and applications; applications of coding in cryptography; cryp- graphy; cryptanalysis; and network security and protocols. These topic headings represent the breadth of activity in the areas of coding, cryptography and c- munications, and the rich interplay between these areas. Assemblingtheconferenceprogrammeandthisproceedingsrequiredthehelp of many individuals. I would like to record my appreciation of them here. Firstly, I would like to thank the programme committee who aided me – mensely by evaluating the submissions, providing detailed written feedback for the authors of many of the papers, and advising me at many critical points – ring the process. Their help and cooperation was essential, especially in view of the short amount of time available to conduct the reviewing task. The c- mittee this year consisted of Mike Darnell, Mick Ganley, Bahram Honary, Chris Mitchell, Matthew Parker, Nigel Smart and Mike Walker.