Privacy preserving asset transfer between networks

1 . A system, comprising:

a processor;

a memory on which are stored machine-readable instructions that when executed by the processor, cause the processor to:

connect to a first blockchain network configured to store user assets, the first blockchain network in communication with a second blockchain network;

receive login data from a user;

receive an asset pledge transaction for an asset on the first blockchain network from the user identified by the login data, the asset pledge transaction including i) a first unique identifier of the asset, ii) a digital signature of the user, iii) identification data of: the user, a recipient, a deadline, the first blockchain network, the second blockchain network as a destination network, asset type, asset value, a second unique identifier of the asset, iv) a randomization of a zero-knowledge asset transfer token (ZKAT) encoding the user as an owner of the asset, and v) a first zero-knowledge proof (ZKP) showing that the second unique identifier is a randomization of an existing token of the first blockchain network;

confirm that the user is an owner of the asset based on a previous asset transfer transaction associated with the user;

verify availability of the asset based on the ZKP and first blockchain network records;

determine that the recipient is a registered user of the second blockchain network;

assign the asset to the first unique identifier of an asset pledge script;

receive a pledge proof request, from the recipient prior to expiration of the deadline, the pledge proof request comprising the first unique identifier; and

respond to the pledge proof request with a signature of the first blockchain network;

receive, by a second participating node of the second blockchain network, a claim transaction including the second unique identifier of the asset, the deadline, a second ZKAT encoding the recipient as an owner of the asset, a second ZKP, and a signature of the recipient; and

add, by the second participating node of the second blockchain network, the second ZKAT, and the second unique identifier of the asset to the second blockchain network.

2 . The system of claim 1 , wherein the asset pledge comprises the first unique identifier that allows the network to identify the pledged token and sign its content.

3 . The system of claim 1 , wherein the first unique identifier is determined according to at least a private key of the user.

4 . The system of claim 1 , wherein the identification data of: the user, a recipient, a deadline, the first blockchain network, the second blockchain network as a destination network, asset type, asset value, a second unique identifier of the asset comprises a hiding commitment of the user, the recipient, the deadline, the first blockchain network, the second blockchain network, the asset type, and the asset value, and the second unique identifier.

5 . The system of claim 1 , wherein digital signature of the user comprises an anonymous signature.

6 . The system of claim 1 , wherein digital signature of the recipient comprises an anonymous signature.

7 . A method, comprising:

connecting, by a participating node, to a first blockchain network configured to store user assets, the first blockchain network in communication with a second blockchain network;

receiving, by the participating node login data from a user;

receiving, by the participating node, an asset pledge transaction for an asset on the first blockchain network from the user identified by the login data, the asset pledge transaction including i) a first unique identifier of the asset, ii) a digital signature of the user, iii) identification data of: the user, a recipient, a deadline, the first blockchain network, the second blockchain network as a destination network, asset type, asset value, a second unique identifier of the asset, iv) a randomization of a zero-knowledge asset transfer token (ZKAT) encoding the user as an owner of the asset, and v) a first zero-knowledge proof (ZKP) showing that the second unique identifier is a randomization of an existing token of the first blockchain network;

confirming, by the participating node, that the user is an owner of the asset based on a previous asset transfer transaction associated with the user;

verifying, by the participating node, an availability of the asset based on the ZKP and first blockchain network records;

determining, by the participating node, that the recipient is a registered user of the second blockchain network;

assigning, by the participating node, the asset to the first unique identifier of the asset pledge transaction;

receiving, by the participating node, a pledge proof request, from the recipient prior to expiration of the deadline, the pledge proof request comprising the first unique identifier; and

responding to the pledge proof request with a signature of the first blockchain network;

receiving by a second participating node of the second blockchain network, a claim transaction including the second unique identifier of the asset, the deadline, a second ZKAT encoding the recipient as an owner of the asset, a second ZKP, and a signature of the recipient; and

adding, by the second participating node of the second blockchain network, the second ZKAT, and the second unique identifier of the asset to the second blockchain network.

8 . The method of claim 7 , wherein the asset pledge transaction further comprises the first unique identifier that allows the network to identify the pledged token and sign its content.

9 . The method of claim 7 , wherein the first unique identifier is determined according to at least a private key of the user.

10 . The method of claim 7 , wherein the identification data of: the user, a recipient, a deadline, the first blockchain network, the second blockchain network as a destination network, asset type, asset value, a second unique identifier of the asset comprises a hiding commitment of the user, the recipient, the deadline, the first blockchain network, the second blockchain network, the asset type, and the asset value, and the second unique identifier.

11 . The method of claim 7 , wherein digital signature of the user comprises an anonymous signature.

12 . The method of claim 7 , wherein digital signature of the recipient comprises an anonymous signature.

13 . A non-transitory computer readable medium comprising instructions, that when read by a processor of a participating node, cause the processor to:

connect to a first blockchain network configured to store user assets, the first blockchain network in communication with a second blockchain network;

receive login data from a user;

receive an asset pledge transaction for an asset on the first blockchain network from the user identified by the login data, the asset pledge transaction including i) a first unique identifier of the asset, ii) a digital signature of the user, iii) identification data of: the user, a recipient, a deadline, the first blockchain network, the second blockchain network as a destination network, asset type, asset value, a second unique identifier of the asset, iv) a randomization of a zero-knowledge asset transfer token (ZKAT) encoding the user as an owner of the asset, and v) a first zero-knowledge proof (ZKP) showing that the second unique identifier is a randomization of an existing token of the first blockchain network;

confirm that the user is an owner of the asset based on a previous asset transfer transaction associated with the user;

verify availability of the asset based on the ZKP and first blockchain network records;

determine that the recipient is a registered user of the second blockchain network;

assign the asset to the first unique identifier of an asset pledge script;

receive a pledge proof request, from the recipient prior to expiration of the deadline, the pledge proof request comprising the first unique identifier; and

respond to the pledge proof request with a signature of the first blockchain network;

receive, by a second participating node of the second blockchain network, a claim transaction including the second unique identifier of the asset, the deadline, a second ZKAT encoding the recipient as an owner of the asset, a second ZKP, and a signature of the recipient; and

add, by the second participating node of the second blockchain network, the second ZKAT, and the second unique identifier of the asset to the second blockchain network.

14 . The non-transitory computer readable medium of claim 13 ,

wherein the asset pledge transaction further comprises the first unique identifier that allows the network to identify the pledged token and sign its content.

15 . The non-transitory computer readable medium of claim 13 , wherein the first unique identifier is determined according to at least a private key of the user.

16 . The non-transitory computer readable medium of claim 13 ,

wherein the identification data of: the user, a recipient, a deadline, the first blockchain network, the second blockchain network as a destination network, asset type, asset value, a second unique identifier of the asset comprises a hiding commitment of the user, the recipient, the deadline, the first blockchain network, the second blockchain network, the asset type, and the asset value, and the second unique identifier.

17 . The non-transitory computer readable medium of claim 13 , wherein the digital signature of the user comprises an anonymous signature.