any open BD Content Hash Table verifier?

[jemima]

Hey.

I just wondered whether anyone here ever stumbled over some open source implementation of a verifier for the hashsums in the Content Hash Table of BluRays?

MakeMKV does it when it makes a copy, but I'd like to have a standalone tool (e.g. for just checking the medium or verifying an image dump of the BluRay).

The algorithm is explained in https://aacsla.com/wp-content/uploads/2 ... ed.921.pdf on page 22, ff..

Shouldn't be too hard to implement, but I figured why re-inventing the wheel, if one could be lazy instead.

Thanks,
Jemima

[segfaulted]

There's one little caveat which might explain why no such tool exists yet. From page 10 of that document:

If the data is encrypted, the encrypted data itself is used as an input to the hashing function, so that the player needs not to decrypt the data before calculating a hash value.

That means the content hash table is practically worthless if a backup (of an encrypted disc) is already decrypted.

Maybe such a tool would somehow need to redo the re-encryption in order to be useful, but that's a whole can of worms in itself if someone had to start from scratch.