The judicial system looks at which persons acted with the intent of committing a criminal act.
Are you suggesting the judicial system would treat Bob and Alice as equally guilty because the bits in the xor'ed infringing material are coming equally from both files? That is not how it works. One of them acted with criminal intent, which is the one who will be persecuted.
Of course you can't see from the bits themselves who the guilty party is. But in this hypothetically scenario you could just look at the timestamps on the files.
A person who purchase or download the material is also guilty of copyright infringement. And it doesn't matter if the system can figure out who distributed it in the first place - consuming it is an independent crime.
It doesn't matter if the material was distributed as one unencrypted file or as multiple fragments on different servers which has to be combined or whether it was hidden among public domain material, or any other clever scheme.
Are you suggesting the judicial system would treat Bob and Alice as equally guilty because the bits in the xor'ed infringing material are coming equally from both files? That is not how it works. One of them acted with criminal intent, which is the one who will be persecuted.
Of course you can't see from the bits themselves who the guilty party is. But in this hypothetically scenario you could just look at the timestamps on the files.
A person who purchase or download the material is also guilty of copyright infringement. And it doesn't matter if the system can figure out who distributed it in the first place - consuming it is an independent crime.
It doesn't matter if the material was distributed as one unencrypted file or as multiple fragments on different servers which has to be combined or whether it was hidden among public domain material, or any other clever scheme.