Friday, March 04, 2016

Something I find very exciting. Much more than these silly gravitational waves (only physicists can spend a billion dollars to generate spikes on a graph ;) ).
The first Zero-Knowledge Contingent Payment was successfully carried out on bitcoin. Suppose I have some valuable information I want to sell you.
So we have a chicken and egg problem - I can either send the information first, and then you might not pay; or you might send the payment first and I will not send the information (I may be lying about having it in the first place)
Greg Maxwell, one of the main developers of bitcoin, described a clever method where either both things happen at once, or don't happen at all.That is, either both money and information changed hands, or neither.
You can think of the method roughly like this. The seller generates a digital key.
At first this key is useless. But then through a process involving the bitcoin network, and something called zero-knowledge proofs, this key is given the power to unlock doors to two rooms - one containing money that the buyer stored for the seller, and another containing the valuable information the buyer wants. Well, by this description you could think, the seller can now only unlock the door containing the money. But the way this is implemented, unlocking that door corresponds to publishing the key on the bitcoin network, after which the buyer can use the key to unlock the second door and get what he paid for.
In a recent conference, a contingent payment was used for the first time to buy a solution to a sudoku puzzle for 0.1 bitcoin - about 40 dollars :)
https://bitcoincore.org/en/2016/02/26/zero-knowledge-contingent-payments-announcement/

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Hi! I am a computer science postdoc. For some reason google is not finding my new homepage so I added a link from this profile