Method and system for merchant acceptance of cryptocurrency via payment rails

A method using a processing server comprising an account database, a receiver and a transmitter for acceptance of blockchain payment at a traditional point of sale device of a merchant, comprising:

• receiving, by the processing server via the receiver, an authorization request for a fiat payment transaction from a point of sale device of the merchant via a payment network, wherein the fiat payment transaction is initiated by a user, wherein the authorization request includes at least a transaction account number of the user, a transaction amount in a fiat currency, and a merchant identifier of the merchant;
• identifying, by the processing server, blockchain payment acceptance for a transaction account of the user associated with the transaction account number included in the authorization request;
• in response to identifying the blockchain payment acceptance for the transaction account, transmitting, by the processing server via the transmitter, an address request to an exchange server, the address request including the merchant identifier;
• based on the received merchant identifier included in the address request, generating, by the exchange server, a recipient blockchain address using a merchant public key associated with a merchant blockchain wallet;
• sending, by the exchange server to the processing server, a response, wherein the response comprises a destination blockchain address and a network identifier of the blockchain network, wherein the destination blockchain address is the recipient blockchain address associated with the merchant blockchain wallet;
• receiving, by the processing server via the receiver, the response from the exchange server;
• based on the received response, transmitting, by the processing server via the transmitter, a new blockchain transaction to a blockchain node in the blockchain network, the new blockchain transaction including at least the recipient blockchain address, a cryptocurrency amount based on the transaction amount and an exchange rate provided by the exchange server, a digital signature, and one or more of the unspent transaction outputs, wherein the blockchain node processes the new blockchain transaction by including it in a new block that is confirmed by other nodes in the blockchain network;
• and
• transmitting, by the processing server via the transmitter, an authorization response for the fiat payment transaction to the payment network for routing to the point of sale device, wherein the authorization response includes a response code indicating that clearance and settlement of the fiat payment transaction is not required.