I'd say showing a host is hosting a copyrighted file is the main way this is proven, and it's hard to host a file without broadcasting evidence of guilt. This i

I'd say showing a host is hosting a copyrighted file is the main way this is proven, and it's hard to host a file without broadcasting evidence of guilt. This is in no way comparable to possessing a murder weapon. > You said yourself you generated the key data with no knowledge of the infringing content, so that makes them distinct. The 'key' differs by history, which isn't know from looking at the bits. There is no way to distinguish which is the key without knowing how they where generated. But by "distinct" I mean that you cannot switch the roles of key and encrypted data in most encryption schemes, that is not true in this case. > Size of the key is the only difference with this scheme compared to more typical ones. That's not true, in traditional schemes the key of any size is still the key in how it's used to decrypt the encrypted data; you cannot decrypt the key using the encrypted data as a key; this is not true for OFFsystem - there is no key/data distinction, if E is the decryption function then E(A, B) = E(B, A)