System for securing verification key from alteration and verifying validity of a proof of correctness

Patent metadata

Field	Value
Publication number	US-12407693-B2
Application number	US-202418667910-A
Country	US
Kind code	B2
Filing date	May 17, 2024
Priority date	Nov 9, 2017
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

The invention relates to distributed ledger technologies such as consensus-based blockchains. A blockchain transaction may include digital resources that are encumbered by a locking script that encodes a set of conditions that must be fulfilled before the encumbered resources may be used (e.g., transferring ownership/control of encumbered resources). A worker (e.g., a computer system) performs one or more computations to generate a proof, which is encoded as part of an unlocking script. A verification algorithm may utilize the proof, a verification key, and additional data such as a cryptographic material associated with the worker (e.g., a digital signature) to verify that digital assets of the transaction should be transferred. As a result of the validation of this transaction, any third party is able to check the contract was executed corrected rather than re-executing the contract, thus saving computational power.

First claim

What is claimed is:

1. A computer-implemented method of controlling transfer of a digital asset via a blockchain, the method comprising:
generating a transaction output of a transaction comprising an indication of a digital asset and a locking script that encodes a set of conditions for transferring control of the digital asset, satisfaction of the set of conditions to be determined based at least in part on a verification key and a proof;
generating a transaction input of the transaction, the transaction input comprising:
an identifier associated with the transaction output; and
an unlocking script comprising the proof and a redeem script; and
verifying the set of conditions are satisfied based at least in part on the locking script and the unlocking script;
transferring control of the digital asset in response to verifying satisfaction of the set of conditions;
determining a size of the redeem script;
if the size of the redeem script does not exceed a predetermined threshold, generating the redeem script comprising the verification key and a script to check a set of constraints; and
if the size of the redeem script exceeds the predetermined threshold, generating the unlocking script that stores one or more elements of the verification key in the part of the unlocking script preceding the redeem script so that the size of the redeem script is within the predetermined threshold, and generating the redeem script with the remaining elements of the verification key and the script to check a set of constraints.

2. The computer-implemented method according to claim 1 , wherein the verification key comprises a first plurality of elements of a finite field and the proof comprises a second plurality of elements of the finite field.

3. The computer-implemented method according to claim 2 , wherein elements of the finite field are points on an elliptic curve.

4. The computer-implemented method according to claim 3 , wherein the elements of the finite field are encoded in a compressed format.

5. The computer-implemented method according to claim 1 , wherein a client encodes the transaction input with the verification key and a first digital certificate associated with the client and a worker encodes the transaction input with the proof and a second digital certificate associated with the worker.

6. The computer-implemented method according to claim 1 , wherein the locking script comprises instructions that, contingent upon a condition of the set of conditions being unsatisfied by the unlocking script, reclaim the digital asset for provider of the digital asset.

7. The computer-implemented method according to claim 6 , wherein:
wherein the verification key and the redeem script are to satisfy the set of conditions; and
the locking script encodes a condition of the set of conditions that a hash of the redeem script matches a predetermined value.

8. The computer-implemented method according to claim 7 , wherein the redeem script is less than or equal to 520 bytes in size.

9. The computer-implemented method according to claim 7 , wherein the unlocking script comprises one or more elements of the verification key.

10. The computer-implemented method according to claim 7 , wherein the transaction is a P2SH transaction in accordance with a Bitcoin based protocol.

11. The computer-implemented method according to claim 1 , wherein the transaction is a standard transaction in accordance with a blockchain-based protocol.

12. The computer-implemented method according to claim 1 , wherein the locking script and unlocking script are encoded in a stack-based scripting language.

13. The computer-implemented method according to claim 1 , wherein the set of conditions comprise a bilinear constraint.

14. A system, comprising:
a processor; and
memory including executable instructions that, as a result of being executed by the processor, cause the system to perform the computer-implemented method according to claim 1 .

15. 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 at least perform the computer-implemented method according to claim 1 .

Assignees

• Nchain Licensing Ag

Inventors

• Covaci Alexandra
• Madeo Simone
• Motylinski Patrick
• Vincent Stephane

Classifications

• H04L9/085

  Secret sharing or secret splitting, e.g. threshold schemes · CPC title

• H04L9/0838

  Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these (network architectures or network communication protocols for key exchange in a packet data network H04L63/061) · CPC title

• H04L9/3239

  involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD · CPC title

• H04L9/3218 Primary

  using proof of knowledge, e.g. Fiat-Shamir, GQ, Schnorr, ornon-interactive zero-knowledge proofs · CPC title

• G06Q20/065

  using e-cash · CPC title