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.

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.

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.