Replay Attack Preventtion System

A method comprising:

• receiving, by a first host computing system and from a first computing device via a network, a token corresponding to an initiated data transaction via near field communication between a first computing device and a second computing device;
• processing, by the first host computing system and by a smart contract based on the token, data transfer parameter information to determine token validity;
• triggering, by the first host computing system and at a second host computing device and based on identification that the token is valid, completion of the data transaction;
• and
• generating, by the first host computing system and by smart contract functionality and in response to triggering completion of the data transaction, a stale token.

A near field communication (NFC) transaction security computing device comprising;

• a processor;
• and
• memory storing computer-readable instructions that, when executed by the processor,
• cause the NFC transaction security computing device to:
• receive, from a first computing device via a network, a token corresponding to an initiated NFC data transaction between the first computing device and a second computing device;
• process, based on the token, data transfer parameter information to determine token validity;
• trigger, at a second host computing device and based on identification that the token is valid, completion of the NFC data transaction;
• and
• generate, by smart contract functionality and in response to triggering completion of the NFC data transaction, a stale token.