cksumvfs.c uses an **8-byte** checksum, 64-bits, not an 8-bit checksum. Is that a typo in your original post, or a fundamental misunderstanding? If you are after a 16-byte, 128-bit checksum, I think the cksumvfs.c source file would be a good starting point. Just swap out the "cksmCompute()" function with whatever 128-bit checksum algorithm you have in mind, and make a few other strategic "8"-to-"16" edits, and you should be good to go.