TRANSFERRING LEDGER ASSETS BETWEEN BLOCKCHAINS VIA PEGGED SIDECHAINS

• US 20160330034A1
• Filed: 05/09/2016
• Published: 11/10/2016
• Est. Priority Date: 05/07/2015
• Status: Active Grant

• Current Assignee: Blockstream Corp.
• Original Assignee: Blockstream Corp.
• Inventors: BACK, Adam, MAXWELL, Gregory
• Granted Patent: US 10,812,274 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06Q 20/06 Private payment circuits, e.g. involving electronic currency used among participants of a common payment scheme
• CPC Class Codes: G06Q 20/065 using e-cash
• CPC Class Codes: G06Q 20/0655 e-cash managed centrally
• CPC Class Codes: G06Q 20/401 Transaction verification
• CPC Class Codes: G06Q 40/12 Accounting
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/3255 using group based signatures, e.g. ring or threshold signatures
• CPC Class Codes: H04L 9/50 using hash chains, e.g. blockchains or hash trees

Abstract

Systems and methods are described for transferring an asset from a parent chain to a sidechain. A simplified payment verification (SPV) proof associated with the parent chain asset may be generated. The SPV proof may include a threshold level of work. The SPV proof associated with the parent chain asset may be validated, and a sidechain asset corresponding to the parent chain asset may be generated. If no reorganization proof is detected, the sidechain asset is released. To redeem the sidechain asset in the parent chain, a SPV proof associated with the sidechain asset may be generated. The parent chain may validate the SPV proof associated with the sidechain asset. The parent chain asset associated with the sidechain asset may be held for a second predetermined contest period. The parent chain asset may then be released if no reorganization proof associated with the sidechain asset is detected.

Claims

1. A method for transferring an asset from a parent chain to a sidechain, the method comprising:

sending, by a processor, a parent chain asset to an output of the parent chain;

generating, by the processor for the output, a simplified payment verification (SPV) proof associated with the parent chain asset, the SPV proof comprising a threshold level of work, the generating taking place over a predetermined period of time;

validating, by a sidechain validator server, that the SPV proof associated with the parent chain asset meets the threshold level of work indicated by the SPV proof;

generating a sidechain asset corresponding to the parent chain asset;

holding the sidechain asset for a predetermined contest period, during which the transferring is invalidated if a reorganization proof associated with the parent chain asset is detected in the parent chain;

releasing the sidechain asset if no reorganization proof is detected;

sending, by a second processor, the sidechain asset to an output of the sidechain;

generating, by the second processor, a SPV proof associated with the sidechain asset;

validating, by a parent chain validator server, the SPV proof associated with the sidechain asset;

holding the parent chain asset for a second predetermined contest period, during which a release of the parent chain asset is denied if a reorganization proof associated with the sidechain asset is detected in the sidechain; and

releasing the parent chain asset if no reorganization proof associated with the sidechain asset is detected.

2. The method of claim 1, the validating the SPV proof associated with the sidechain asset comprising validating, by the parent validator server, that the SPV proof associated with the sidechain asset meets the threshold level of work indicated by the SPV proof associated with the sidechain asset, the method further comprising:

when release of the parent chain asset is denied, receiving a second SPV proof associated with the sidechain asset;

validating the second SPV proof associated with the sidechain asset;

holding the parent chain asset for a third predetermined contest period, during which a release of the parent chain asset is denied if a reorganization proof associated with the sidechain asset is detected in the sidechain; and

releasing the parent chain asset if no reorganization proof associated with the sidechain asset is detected.

3. The method of claim 1, wherein the predetermined contest period has a duration that is a function of a relative hashpower of the parent chain and the sidechain.

4. The method of claim 1, wherein the non-linear filter has a definition of, with a threshold function defined as.

5. The method of claim 1, wherein the sidechain asset differs from the parent asset in one of block structure and transaction chaining.

6. The method of claim 1, wherein the sidechain asset utilizes a ring signature scheme.

7. The method of claim 1, the sidechain asset further comprising script extensions not present in the parent chain asset.

8. The method of claim 1, wherein the sidechain supports demurrage for sidechain assets.

9. The method of claim 1, wherein the sidechain supports smart property.

10. A method for transferring an asset from a parent chain to a sidechain, the method comprising:

validating, by a sidechain validator server, a parent chain asset in response to receiving, by the sidechain validator server, a request to transfer the parent chain asset to the sidechain, the validating comprising determining if a proof of work associated with the parent chain asset is valid;

generating a sidechain asset corresponding to the parent chain asset in response to determining that the proof of work is valid;

sending the sidechain asset to an output of the sidechain in response to a request to transfer the sidechain asset back to the parent chain;

generating a simplified payment verification (SPV) proof associated with the sidechain asset;

validating, by the parent chain, the SPV proof associated with the sidechain;

holding the parent chain asset for a predetermined contest period, during which a release of the parent chain asset is denied if a reorganization proof associated with the sidechain asset is detected in the sidechain; and

releasing the parent chain asset if no reorganization proof associated with the sidechain asset is detected.

11. The method of claim 10, the generating the sidechain asset further comprising sending the parent chain asset to a federated peg, the federated peg comprising a plurality of functionaries, wherein at least one functionary generates a SPV proof associated with the parent chain asset, the SPV proof comprising a threshold level of work, the generating taking place over a predetermined period of time, the method further comprising activating, by a server of the federated peg, the generated sidechain asset in response to receiving a nonce, a ScriptPubKey, and the generated SPV proof, the activating the sidechain asset allowing the sidechain asset to be transferred within the sidechain.

12. The method of claim 11, wherein the federated peg is not monitored by blockchains of the parent chain.

13. A method for creating and verifying a compressed version of a simplified payment verification (SPV) proof, the method comprising:

generating a blockheader for a block of a parent chain asset, the blockheader comprising a plurality of commitments, each commitment being associated with one of a plurality of past headers before the blockheader in a block history associated with the parent asset;

storing the plurality of commitments of the generated blockheader in a Merkle tree; and

verifying the validity of the blockheader, the verifying comprising;

extracting the plurality of commitments;

checking a block greater than one link back in the plurality of past headers; and

verifying, based on the checked block, that a work amount indicated by the blockheader exceeds a total target work proven by following direct predecessor links of the blockheader.

14. The method of claim 13, wherein the checking the block is performed on a block within a maximum skip size of a most recent block.

15. The method of claim 14, wherein the maximum skip size dynamically increases with the amount of work being proven.

16. The method of claim 13, wherein the verifying further comprises revealing random committed blockheaders using part of the SPV proof as a random seed.