What happens in the case of plausibly-deniable keys? Say someone has an encrypted drive with a hidden volume, one key decrypts decoy files and one decrypts the true files. If the person gives up the key to the decoy files, is the onus on the prosecution to prove additional keys exist or on the defence to prove they don't?
Not a lawyer but I expect it would be on prosecution to convince a jury that they had failed to make "a disclosure of any key to the protected information that is in his possession"
as per RIPA 2000 Section 50, 2 a)
To do this, they'd likely need some evidence to persuade the jury, beyond reasonable doubt, that the encryption system had such a feature.
