This book constitutes the thoroughly refereed post-proceedings of the 9th International Workshop on Information Hiding, IH 2007, held in Saint Malo, France, in June 2007.

The 25 revised full papers presented were carefully reviewed and selected from 105 submissions. The papers are organized in topical sections on new steganographic schemes, watermarking schemes, computer security, steganography and code theory, watermarking security, steganalysis, watermarking and re-synchronization, fingerprinting, forensics, and steganalysis.

We are glad to present in this volume the proceedings of the ninth edition of Information Hiding (IH 2007). The conference was held in Saint Malo, the C- sairs town, France, during June 11-13, 2007. It was organized by a team of four Frenchpiratessupported by the valuablehelp of the conferenceorganizationcell of INRIA Rennes. Continuing the tradition of the previous editions, we tried to provide a b- anced program covering the di?erent aspects of information hiding. This being said, the selection of the program was a very challenging task. This year, 105 papers from 25 countries were submitted. This was the highest number of s- missions in IH history. We would like to take the opportunity to thank all the authors who submitted a paper to IH 2007 and thus contributed to consolidate the reputation of this conference. Each paper was refereed by at least three reviewers. Since this event was run with a single track, it implied that only 25 papers were accepted for presentation. This unusually low acceptance rate will further promote Information Hiding as the top forum of our community. Although watermarking and steganography still receive most of the interest, new topics emerged during the conference such as the use of Tardos codes for ?ngerprinting and digital forensics. We would like to thank all the members of the Program Committee and all the external reviewers for the enormous e?ort that they put into the reviewing process.