Tarsnap is not open source, so I intentionally avoided looking at the code to avoid any doubt over provenance. I imagine it would be harder, since Tarsnap is ba

Tarsnap is not open source, so I intentionally avoided looking at the code to avoid any doubt over provenance. I imagine it would be harder, since Tarsnap is backed by S3 and AIUI Colin's own transactional storage layer to make it work with S3.