Atomic swap token trades

A computer-implemented method of accepting a token transferred using a blockchain, wherein the blockchain comprises a token issuance transaction, wherein the token issuance transaction comprises token data and an output locked to a public key an issuing party, and wherein the method is performed by a receiving party and comprises:

• receiving a first blockchain transaction from a sending party via an off-chain communication channel;
• verifying that the first blockchain transaction comprises a first input that references an output of the token issuance transaction or an output of a previous blockchain transaction that forms part of a chain of one or more previous blockchain transactions linking to the token issuance transaction, wherein the referenced output is locked to a first public key of the sending party;
• verifying that a first output of the first blockchain transaction is cryptographically locked to a public key of the receiving party;
• generating a funded first blockchain transaction by including one or more respective inputs in the first blockchain transaction that reference one or more respective outputs of one or more respective funding transactions, the one or more respective outputs being cryptographically locked to one or more respective public keys of the receiving party, wherein the funded first blockchain transaction comprises a second output cryptographically locked to a public key of the receiving party, the second output comprising token data;
• sending the funded first blockchain transaction to the sending party via an off-chain communication channel, wherein the sending party is configured to verify that the one or more respective funding transactions are on the blockchain and verify that a second output of the funded first transaction is locked to a public key of the sending party and locks a predetermined amount of digital asset, and if so, generate a signed first transaction by including a signature in the first input of the funded first transaction, wherein the signature corresponds to the first public key of the sending party, and send the signed first transaction to one or more nodes of a blockchain network and/or to the receiving party.

A non-transitory computer readable medium comprising a computer program configured so as, when run on one or more processors, the one or more processors perform a computer-implemented method of transferring a token using a blockchain, wherein the blockchain comprises a token issuance transaction, wherein the token issuance transaction comprises token data and an output locked to a public key of an issuing party, and wherein the method is performed by a sending party and comprises:

• generating a first blockchain transaction, wherein generating the first transaction comprises:
• generating a first input of the first blockchain transaction that include a reference referencing an output of the token issuance transaction or an output of a previous transaction that forms part of a chain of one or more previous transactions linking to the token issuance transaction, wherein the referenced output is locked to a first public key of the sending party,
• generating a first output of the first blockchain transaction, including constructing a locking script configured to cryptographically lock the first output to a public key of a receiving party, and encoding token data into the first output, and
• generating a second output of the first blockchain transaction, including constructing a locking script configured to cryptographically lock the first output to a public key of the sending party;
• sending the first blockchain transaction to a receiving party, wherein the receiving party is configured to verify that the first input references the output of the token issuance transaction or the output of the previous transaction that forms part of the chain of one or more previous transactions linking to the token issuance transaction, and verify that the first output is locked to the public key of the receiving party, and if so, generate a funded first transaction by including one or more respective inputs in the first transaction that reference one or more respective outputs of one or more respective funding transactions, the one or more respective outputs being locked to one or more respective public keys of the receiving party;
• receiving the funded first blockchain transaction from the receiving party;
• verifying that the second output locked to the public key of the sending party locks a predetermined amount of digital asset, and if so, generating a signed first transaction by:
• generating a digital signature using a private key corresponding to the first public key of the sending party, and
• including the digital signature in the first input of the funded first transaction, wherein the signature;
• and
• sending the signed first blockchain transaction to one or more nodes of a blockchain network and/or to the receiving party.