Checkout with MAC

A system that performs multi-party authentication among participants in an electronic communication operation on behalf of a first party using a shared challenge, the system comprising:

• a third party functionally connected to a second party by a second network, the third party including a second cryptographic function, wherein the third party is configured to:
• responsive to a confirmation of a challenge, receive, from the second party, the challenge, a message authentication code (MAC) formed from an encryption of the challenge with a first key, and transaction details associated with a purchase transaction;
• select a payment instrument based on confirmation of an authentication of the challenge,
• decrypt the MAC using a second key of the first party to generate a decrypted challenge;
• responsive to confirming that the decrypted challenge matches the challenge, retrieve a personal account number (PAN) of the payment instrument of a user from a database and adding the PAN to the transaction details;
• and
• send the transaction details to an issuer of the payment instrument for approval of the purchase transaction.

A computer-implemented method for multi-party authentication for a purchase transaction, comprising:

• responsive to a confirmation of a challenge, receiving, at a processor from a merchant system, the challenge, a message authentication code (MAC) formed from an encryption of the challenge with a first key, and transaction details associated with a purchase transaction;
• decrypting, at the processor, the MAC to generate a decrypted challenge;
• confirming, at the processor, that the decrypted challenge matches the challenge;
• based on the confirming that the decrypted challenge matches the challenge, selecting, by the processor, a payment instrument on a wallet application;
• responsive to confirming that the decrypted challenge matches the challenge, retrieving, by the processor, a personal account number (PAN) of the payment instrument of a user device from a database and adding the PAN to the transaction details;
• and
• sending, by the processor to an issuer of the payment instrument, the transaction details from the processor to the issuer of the payment instrument for approval of the purchase transaction.