Verifiable audit trails for a versioning file system

We present constructs that create, manage, and verify digital audit trails for versioning file systems. Based upon a small amount of data published to a third party, a file system commits to a version history. At a later date, an auditor uses the published data to verify the contents of the file system at any point in time. Audit trails create an analog of the paper audit process for file data, helping to meet the requirements of electronic record legislation, such as Sarbanes-Oxley. Our techniques address the I/O and computational efficiency of generating and verifying audit trails, the aggregation of audit information in directory hierarchies, and constructing verifiable audit trails in the presence of lost data.