# US 12,217,246 B2 · Method and system for use of an EMV card in a multi-signature wallet for cryptocurrency transactions

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- Number: US 12,217,246 B2
- Document ID: US12217246B2
- Status: Granted
- Kind: B2
- Application number: 16/840,566
- Filed: 2020-04-06
- Published: 2021-10-07
- Granted: 2025-02-04
- Earliest claimed: 2020-04-06
- Assignees: Mastercard Asia/Pacific Pte. Ltd.
- Applicants: Mastercard Asia/Pacific Pte. Ltd.
- Inventors: Srinath Ravinathan; Bensam Joyson; Donghao Huang; Teck Yong Tan
- Web page: https://patentgrep.com/patent/US12217246B2

## CPC

- G06Q 20/065: {using e-cash}
- G06Q 20/3678: {e-cash details, e.g. blinded, divisible or detecting double spending}
- G06F 16/27: Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
- G06Q 20/02: involving a neutral party, e.g. certification authority, notary or trusted third party [TTP]
- G06Q 20/0658: {e-cash managed locally}
- G06Q 20/202: {Interconnection or interaction of plural electronic cash registers [ECR] or to host computer, e.g. network details, transfer of information from host to ECR or from ECR to ECR}
- G06Q 20/341: {Active cards, i.e. cards including their own processing means, e.g. including an IC or chip}
- G06Q 20/3674: {involving authentication}
- G06Q 20/3825: {Use of electronic signatures}
- G06Q 20/3829: {involving key management}
- H04L 9/3255: {using group based signatures, e.g. ring or threshold signatures}
- H04L 9/50: {using hash chains, e.g. blockchains or hash trees}
- G06Q 2220/00: Business processing using cryptography
- G06Q 2220/10: Usage protection of distributed data files
- H04L 2209/56: Financial cryptography, e.g. electronic payment or e-cash
- G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A method for carrying out a cryptocurrency blockchain transaction through an integrated circuit payment card using a multi-signature blockchain wallet includes: storing, in an integrated circuit of a payment card, a first private key of a first cryptographic key pair and a transaction account number; receiving, by the integrated circuit, a blockchain transaction from a point of sale device, the blockchain transaction including unspent transaction outputs, destination addresses, a cryptocurrency amount for each destination address, and a first digital signature generated using a second private key of a second cryptographic key pair; digitally signing, by the integrated circuit, the blockchain transaction using the first private key to generate a second digital signature; and transmitting, by the integrated circuit, the digitally signed blockchain transaction including the first digital signature and the second digital signature to the point of sale device.

## Claims

### Claim 1

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:
storing, in a memory of an integrated circuit of a payment card, 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;
receiving, by a receiver of the integrated circuit, transaction data from a point of sale device, the transaction data including a transaction amount and a transaction identifier;
transmitting, by a transmitter of the integrated circuit, the transaction account number to the point of sale device in response to the transaction data prior to generating a blockchain transaction;
receiving, by the receiver of the integrated circuit, 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;
generating, by the integrated circuit, a blockchain transaction using the received blockchain data;
validating, by a processor of the integrated circuit, the first digital signature using the second public key of the second cryptographic key pair;
in response to validating the first digital signature, digitally signing, by the processor of the integrated circuit, the blockchain transaction using the first private key to generate a second digital signature; and
transmitting, by the transmitter of the integrated circuit, the digitally signed blockchain transaction including the first digital signature and the second digital signature to the point of sale device.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
receiving, by an acquiring financial institution, the digitally signed blockchain transaction from the point of sale device; and
transmitting, by the acquiring financial institution, the digitally signed blockchain transaction to a blockchain node in a blockchain network.

### Claim 3 (depends on 1)

The method of claim 1, wherein,
the memory of the integrated circuit further includes a first public key of the first cryptographic key pair, and
the transmission of the digitally signed blockchain transaction further includes the first public key.

### Claim 4 (depends on 3)

The method of claim 3, further comprising:
validating, by the point of sale device, the second digital signature using the first public key.

### Claim 5 (depends on 3)

The method of claim 3, further comprising:
validating, by an acquiring financial institution, the second digital signature using the first public key.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
transmitting, by the point of sale device, the transaction account number to the issuing financial institution;
receiving, by the issuing financial institution, the transaction account number from the point of sale device;
identifying, by the issuing financial institution, an account profile using the transaction account number, the account profile including the one or more unspent transaction outputs; and
transmitting, by the issuing financial institution, the one or more unspent transaction outputs to the point of sale device.

### Claim 7

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.

### Claim 8 (depends on 7)

The system of claim 7, further comprising:
a blockchain network including a blockchain node; and
an acquiring financial institution, wherein the acquiring financial institution
receives the digitally signed blockchain transaction from the point of sale device, and
transmits the digitally signed blockchain transaction to the blockchain node.

### Claim 9 (depends on 7)

The system of claim 7, wherein,
the memory of the integrated circuit further includes a first public key of the first cryptographic key pair, and
the transmission of the digitally signed blockchain transaction further includes the first public key.

### Claim 10 (depends on 9)

The system of claim 9, wherein the point of sale device validates the second digital signature using the first public key.

### Claim 11 (depends on 9)

The system of claim 9, further comprising:
an acquiring financial institution validating the second digital signature using the first public key.

### Claim 12 (depends on 7)

The system of claim 7, wherein the point of sale device includes a transmitter transmitting the transaction account number to the issuing financial institution; and
wherein the issuing financial institution includes:
a receiver receiving the transaction account number from the point of sale device;
a processor identifying an account profile using the transaction account number, the account profile including the one or more unspent transaction outputs, and
a transmitter transmitting the one or more unspent transaction outputs to the point of sale device.

### Claim 13

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.

### Claim 14 (depends on 13)

The method of claim 13, comprising:
receiving, by the acquiring financial institution via the payment network, the digitally signed blockchain transaction from the processing device; and
transmitting, by the acquiring financial institution, the digitally signed blockchain transaction to a blockchain node in a blockchain network.

### Claim 15 (depends on 13)

The method of claim 13, wherein,
the blockchain transaction digitally signed with the second digital signature includes the first public key.

### Claim 16 (depends on 15)

The method of claim 15, comprising:
validating, by the processing device of the point of sale device, the second digital signature using the first public key.