Matthew Skala's excellent "Color of Bits" article is, ten years later, still the best translation of copyright law for the use of computer people.i
Meditation upon it has also inspired the current article, which is a proposition of a better torrent system, sadly bereft of technical detail of implementationii. To understand the matters proposed one has to have some familiarity with number-theoretic mathematics, or at least some practical understanding of cryptography enough to know what malleability is.
I. Torrenting as it works now. A large number X is split into fixed length numbers x1...xn. An index list of these x1...xn items is held somewhereiii. Clients interested in acquiring X will obtain the list of x1...xn fragments and the list of active other clients, and proceed to exchange the xi they have for the xi others have until each i from 1 to n is represented at least once in their collection, at which point "the download is complete". Most systems rely on some upload redundancy, in the sense that most clients should give out more i bits than n, generally by a margin of about 50%.
II. Torrenting as it is proposed to work. A large number X is split into fixed length numbers x1... xn. Each of these x1 numbers is put through mystery function F, with the property that while F(xi) exists for every i in [1, n], a F' does not exist so that F'(F(xi)) = xi for any i in [1,n] and moreover that a F'', Γiv pair also doesn't exist so that F''( Γ (F(xi), (i in [1..n])) = X. In plain human language, one needs to be able to calculate a hash of each fragment but not be able to recoup the fragment from the hash nor the whole number from the whole collection of fragment hashes.
This process is repeated by a number of different clients, each using his own F1... Fm, all of which satisfy the same above requirements. And now the fun part starts : the requirement is that for any m over a reasonable value (perhaps 10 ?), a G reverse function DOES exist together with a Γ so that G(Γ (F(xij), (i in [1..n], j in [1..k, k < m]) = X. In plain human language, one needs to be able to recover the original X from a collection of n+k hashes made by different users.
So in practice : you take Smart Money and cut it into Kb sized items. You hash all these. All your friends do the same. You can not obtain your original film from your collection of hashes, nor can they obtain their copy back from their collection of hashes. However, if you obtain a sufficient variety of such bits, say 60% of your set and 55% of Joe's set and 35% of Moe's set and so on and so forth you will eventually be able to bust the film back out of there.
In theory I imagine the case where m = n (so there's as many different users doing the hashing as there's hash fragments) might result in very close to 100% efficiency (ie, you can actually obtain X out of n fragments), whereas lower sample sizes might require more redundancy in the available bits (but ideally even if you only have 10ish sources, you shouldn't need more than say 1.30 to 1.5x n bits to decode X).
The disadvantage of this system, quite obviously, is that it'd need more CPU (or perhaps GPU ?) cycles, and more bandwidth to deliver the same copyright infringing experience - all those things we really have plenty of. The advantage, in case it's not obvious, is complete prosecutorial immunity for any copyright infringement whatsoever, and more generally, for any data sharing of any kindv - all those things we desperately need.
There is no doubt in my mind this can be done. The question, of course, is what will function F be ? I have no idea, quite frankly, I imagine it'd probably be something close to some sort of malleable cypher, perhaps with or perhaps without some help from schemes such as the Lamportized Blockchain.
So now, who's the bright young fellow that's going to define F for us ?
———- I have a lot of respect for people who verify in practice the ability to translate key concepts in one intellectual system in such terms so as to allow consistency of understanding for practitioners skilled in another intellectual system. It is, as far as I can see, the foremost intellectual activity, and certainly to these people belongs the future. They are the new traders of the world, except where the old traders that made the old new world traded spices and slaves for gold and silver, the modern masters of all they survey trade simply ideas. Oh, but what a glorious trade it is, and how nothing else may ever come close! [↩]
- Because I'm not good enough to do that part. [↩]
- Originally by a centralised service called a "tracker", but from what I gather now the respective database is also distributed - you'll have to pardon my very approximate understanding of these things as pretty much everything I know on the topic comes from Bitcoin really. [↩]
- Think of gamma as some sort of intuitive "addition" as conveniently defined for the application. [↩]
- Inasmuch as you can't obtain the alleged infringed/forbidden material from the actual data shared by the actual individual, you will have to change the law to be able to prosecute this activity. And the problem with so changing the law is that you'd have to change it in ways it can't be changed, so this is never happening. [↩]