How can they know the hash value of a file unless they have access to it's decrypted content?
Maybe they did decrypt the drives and do have the unencrypted files, but
a) do not want to admit it (because top secret);
b) are afraid that without disclosure of the exact (top secret) procedure defence will accuse them of fabricating the data ("Your Honor, the prosecution claim these are the drives' contents, but they have not shown how exactly they arrived at this conclusion...");
c) think 'the old razzle dazzle' should be enough (because think of the children) to avoid disclosure of capabilities;
d) hope that 'the hashes match' will become a useful precedent on record - better than 'here are the decrypted files - look at this filth'.
Biting the hand that feeds IT
