System and method for multi-party generation of blockchain-based smart contract
Systems and methods described herein relate to techniques that allow for multiple parties to jointly generate or jointly agree upon the parameters for generation of a smart contract, such as a verification key. Execution of the smart contract may be performed by a third party, for example, a worker node on a blockchain network. Techniques described herein may be utilised as part of a protocol in which parties of a smart contract share powers of a secret in a manner that allows each party to determine an identical common reference string, agree on parameters for a smart contract, agree and/or make proportionate contributions the smart contract, and combinations thereof. The smart contract may be published to a blockchain network (e.g., Bitcoin Cash). The protocol may be a zero-knowledge protocol.
1. A computer-implemented method of executing a smart contract generated by a first computing entity and a second computing entity, the computer-implemented method implemented by a third computing entity different from both the first computing entity and the second computing entity, the computer-implemented method comprising:
receiving, at the third computing entity, the smart contract comprising a first transaction input and an evaluation key Ek provided by the first computing entity and a second transaction input provided by the second computing entity;
executing the smart contract by performing a computational task comprising the computation of a function on an input to the smart contract to produce an output of the smart contract;
producing a proof of correct execution of the smart contract, wherein the proof is based at least in part on the evaluation key Ek;
generating a blockchain transaction using the output of the smart contract; and
validating, by a fourth computing entity different from the first, second, and third computing entities, the generated transaction using a verification key Vk and the proof.
2. The computer-implemented method according to claim 1 , wherein the third computing entity is a node of a blockchain network.
3. The computer-implemented method according to claim 1 , wherein the input comprises information that attests to an identity of the third computing entity.
4. The computer-implemented method according to claim 3 , wherein the information comprises a digital signature generated by a private signature associated with the third computing entity.
5. The computer-implemented method according to claim 1 , wherein the third computing entity receives a transfer of digital assets from at least one of the first computing entity or the second computing entity.
6. The computer-implemented method according to claim 1 , wherein the input provided to the smart contract is provided by at least one of the first computing entity or the second computing entity.
7. The computer-implemented method according to claim 1 , wherein producing the proof of correct execution comprises using an evaluation key.
8. The computer-implemented method according to claim 1 , wherein executing the smart contract to produce the output comprises evaluating internal circuit wires of a quadratic arithmetic program to produce a quadratic arithmetic program output.
9. The computer-implemented method according to claim 8 , wherein the quadratic arithmetic program is of size m and degree d.
10. The computer-implemented method according to claim 1 , wherein the proof of correct execution of the smart contract is stored on a blockchain.
11. The computer-implemented method according to claim 1 , wherein the smart contract comprises a Pay-To-Script-Hash type (P2SH-type) unlocking script that allows the third computing entity to unlock a first digital asset and a second digital asset in response to producing the proof of correct execution.
12. The computer-implemented method according to claim 11 , wherein the P2SH-type unlocking script comprises at least one of: a verification key, an element of the verification key, or a hash of the verification key.
13. A system comprising:
a first processor executing first computing entity;
a second processor executing a second computing entity;
a third processor executing a third computing entity different from both the first computing entity and the second computing entity;
a smart contract generated by the first computing entity and the second computing entity; and
memory including executable instructions of the third computing entity that, as a result of execution by the third processor, causes the system to:
receive the smart contract comprising a first transaction input and an evaluation key Ek provided by the first computing entity and a second transaction input provided by the second computing entity;
execute the smart contract by performing a computational task comprising the computation of a function on an input to the smart contract to produce an output of the smart contract;
produce a proof of correct execution of the smart contract, wherein the proof is based at least in part on the evaluation key Ek;
generate a blockchain transaction using the output of the smart contract; and
validate, by a fourth computing entity different from the first, second, and third computing entities, the generated transaction using a verification key Vk and the proof.
14. A non-transitory computer-readable storage medium having stored thereon executable instructions that, as a result of being executed by a processor of a computer system, cause the computer system to:
receive a smart contract comprising a first transaction input and an evaluation key Ek provided by a first computing entity external to the processor and a second transaction input provided by a second computing entity external to the processor, the processor executing a third computing entity different form the first computing entity and the second computing entity;
execute the smart contract by performing a computational task comprising a computation of a function on an input to the smart contract to produce an output of the smart contract;
produce a proof of correct execution of the smart contract;
generate a blockchain transaction using the output of the smart contract; and
validate, by a fourth computing entity different from the first, second, and third computing entities, the generated transaction using a verification key Vk and the proof.