Method and system for use of an EMV card in a multi-signature wallet for cryptocurrency transactions

A system for carrying out a cryptocurrency blockchain transaction through an integrated circuit payment card using a multi-signature blockchain wallet stored in the integrated circuit payment card, comprising:

• a point of sale device;
• and
• a payment card having an integrated circuit, wherein the integrated circuit includes:
• a memory storing at least a first private key of a first cryptographic key pair, a transaction account number, and a second public key of a second cryptographic key pair, the first cryptographic key pair associated with the multi-signature blockchain wallet and the second cryptographic key pair associated with an issuing financial institution,
• a receiver receiving transaction data from the point of sale device, the transaction data including a transaction amount and a transaction identifier,
• a transmitter transmitting the transaction account number to the point of sale device in response to the transaction data prior to generating a blockchain transaction,
• the receiver receiving blockchain data from the point of sale device via a communication channel, where the blockchain data includes at least one or more unspent transaction outputs associated with the payment card, one or more destination addresses associated with the point of sale device, a cryptocurrency amount for each of the one or more destination addresses, and a first digital signature generated by the issuing institution using a second private key of the second cryptographic key pair, the cryptocurrency amount being equivalent to the transaction amount in the transaction data, and the first digital signature generated in response to an authorization request from an acquiring financial institution linked to the point of sale device;
• a processor generating a blockchain transaction using the received blockchain data;
• the processor validating the first digital signature using the second public key of the second cryptographic key pair;
• the processor, in response to validating the first digital signature, digitally signing the blockchain transaction using the first private key to generate a second digital signature, and
• the transmitter transmitting the digitally signed blockchain transaction including the first digital signature and the second digital signature to the point of sale device.

A method for carrying out a cryptocurrency blockchain transaction through an integrated circuit payment card using a multi-signature blockchain wallet stored in the integrated circuit payment card, comprising:

• detecting, by a processing device of a point of sale device, an integrated circuit payment card for payment of a blockchain transaction;
• establishing, by the processing device of the point of sale device, a communication channel with the integrated circuit payment card;
• transmitting, by the processing device of the point of sale device via the communication channel, transaction data from the point of sale device to the integrated circuit payment card, the transaction data including at least, a transaction amount, and a transaction identifier;
• receiving, by the processing device of the point of sale device via the communication channel, a transaction account number from the integrated circuit payment card;
• transmitting, by the processing device of the point of sale device via a payment network, payment transaction data to an acquiring financial institution prior to receiving a blockchain transaction, the payment transaction data including at least the transaction account number, and the transaction data;
• receiving, by the processing device of the point of sale device via the payment network, blockchain data and a first digital signature of an issuing financial institution associated with the integrated circuit payment card from the acquiring financial institution, the blockchain data including one or more unspent transaction outputs associated with the integrated circuit payment card, one or more destination addresses associated with the point of sale device, and a cryptocurrency amount for each of the one or more destination addresses, the cryptocurrency amount being equivalent to the transaction amount in the transaction data, and the first digital signature generated by the issuing institution using a second private key of a second cryptographic key pair associated with the issuing financial institution;
• transmitting, by the processing device of the point of sale device via the communication channel, the blockchain data and the first digital signature to the integrated circuit payment card;
• receiving, by the processing device of the point of sale device via the communication channel, the blockchain transaction digitally signed with a second digital signature from the integrated circuit payment card, the second digital signature generated by the integrated circuit payment card using a first private key of a first cryptographic key pair associated with the multi-signature blockchain wallet in response to validating the first digital signature;
• and
• transmitting, by the processing device of the point of sale device via the payment network, the digitally signed blockchain transaction including the first digital signature and the second digital signature to the acquiring financial institution.