Zero knowledge proof bitcoin stock
The buyer and seller do not need to trust each other or depend on arbitration by a third party. This type of sale is inherently irreversible, potentially crosses multiple jurisdictions, and involves parties whose financial stability is uncertain—meaning that both parties either take a great deal of risk or have to make difficult arrangement.
Using a ZKCP avoids the significant transactional costs involved in a sale which can otherwise easily go wrong. I played my part in the transaction remotely from California. I first proposed the ZKCP protocol in in an article on zero knowledge proof bitcoin stock Bitcoin Wiki as an example of how tremendously powerful the existing primitives in Bitcoin Script already were. My ZKCP protocol required as a building block a zero-knowledge proof for arbitrary programs. Many kind of specialized zero-knowledge proofs exist: A zero-knowledge proof for general computation is a cryptographic system which lets a person run an arbitrary program with a mixture of public and secret inputs and prove to others that this specific program accepted the inputs, without revealing anything more about its operation or the secret inputs.
As my initial write-up on ZKCP noted, no such system was readily available in but they were believed to be possible, especially under specific constraints that would have worked for ZKCP.
Since then, several groups have continued to advance this work, creating compilers, performance improvements, and most critically, practical tools like libsnark. Zero knowledge proof bitcoin stock of this work, ZKCP can now become a practical tool.
Because these efficient ZKPs are cutting-edge technology which depend on new strong cryptographic assumptions, their security is not settled yet. But in zero knowledge proof bitcoin stock like ZKCP where our only alternatives are third-party trust, they can be used in ways which are a strict improvement over what we could do without them. If you accept the existence of the zero-knowledge proof system as a black box, the rest of zero knowledge proof bitcoin stock ZKCP protocol is quite simple.
The buyer first creates a program that can decide whether the input it is given is the data the buyer wants to buy. This program only verifies the information, it does not produce it—the buyer does not even have to have any idea how to produce it. For example, it is easy to zero knowledge proof bitcoin stock a program to verify that a Sudoku solution is correct, but harder to write a Sudoku solver, Sudoku is NP-complete.
The buyer here only needs to write the solution verifier. The buyer performs the trusted setup for the proof system and sends the resulting setup information over to the seller. The seller sends Ex, Y, the proof, and his pubkey to the buyer. So the buyer initially wanted to buy an input for his program, but now he would be just as happy to buy the preimage of a hash.
As it turns out, Bitcoin already provides a way to sell hash preimages in a secure manner. The effect of this payment is that the seller can collect it if he provides the hash preimage of Y and a signature with his key.
As a result, when the seller collects his payment he is forced to reveal the information that the buyer needs in order to decrypt the answer. This ScriptPubkey is also the same as would be used for a cross-chain atomic swap or a lightning payment channel.
Wallet support for these transactions has been implemented for Bitcoin Core in PR This wallet support is used by the sudoku ZKCP client and server available at https: There are two primary restrictions of this approach. First, that it is interactive: And second, that the ZKP system, while fast enough to be practical, is still not very fast.
For example, in our demo the ZKP system proves 5 executions of SHA and the Sudoku constraints, and takes about 20 seconds to execute on a laptop. The verification of the proof takes only a few milliseconds. In Paypub, instead of using a zero-knowledge proof the buyer is shown a random subset of the data they are attempting to buy, and the seller is forced to unlock the rest when they collect their payment. Paypub avoids the complexity of dealing with a zero-knowledge proof— and also allowing the exchange of information that only humans can verify—, but at the cost of some vulnerability to cheating, and only being usable with a relatively zero knowledge proof bitcoin stock set of randomly verifiable information.
I look forward to the exciting applications people will find for them as the technology becomes increasingly practical. The first successful Zero-Knowledge Contingent Payment. The transfer involved two transactions: See the slides from the live demo.
Background I first proposed the ZKCP protocol in in an article on the Bitcoin Wiki as zero knowledge proof bitcoin stock example of how tremendously powerful the existing primitives in Bitcoin Script already were.
The seller picks a random encryption key and encrypts the information the buyer wishes to buy. Using the ZKP system, the seller proves a composite statement: Y is the sha hash zero knowledge proof bitcoin stock the decryption key for Ex. The buyer makes his payment to the following ScriptPubkey: Recommended View all posts Bitcoin Core 0.
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