Warning
If using Fedora to audit or report the fixity of federated files the "contentBasedSha1" property must be set to "true" in the federation configuration.
When a federated file is first accessed, a sha1 hash is computed and cached. This may take a while for large files. At any point, just like any other node, a request may be made through a web browser or client to recompute and compare the checksum of that file.
In the HTML view, beside the "digest" property for the content, there's a "check fixity" link which will recompute the sha1 and compare it with the last computed one. This feature is documented.
To build a reasonable audit, one needs to:
- ensure that all files are visited/accessed to ensure a baseline sha1 is computed (will take a very long time for larger repositories)
- script a period fixity request against each object which looks for the SUCCESS assertion in the response.
