Secure processing of payment transactions

A payment provider system, comprising a data processing apparatus, the data processing apparatus configured to:

• receive a request for a one-time transaction token from a user for a payment transaction initiated by the user;
• generate, in response to the request, a one-time transaction token;
• store the one-time transaction token;
• provide the one-time transaction token to the user;
• receive the token from an acquirer processing system, the acquirer processing system having received the token from the user, via a transaction processing system;
• validate the received one-time transaction token with the one-time transaction token previously generated;
• if validated, generate transaction payment data and transmit the transaction payment data to the acquirer processing system for it to complete the payment transaction.

An acquirer processing system, comprising a data processing apparatus, the data processing apparatus configured to:

• receive a one-time transaction token from a transaction processing system, the token having been generated by a payment provider system and provided to the transaction processing system by a user;
• identify, based on the received one-time transaction token, the payment provider system which generated the one-time transaction token;
• transmit the one-time transaction token to the identified payment provider system;
• receive, from the identified payment provider system, transaction payment data, the transaction payment data having been generated by the payment provider system after validating the one-time transaction token.