Replay attacks intercept valid data to fraudulently mirror a genuine submission. Attackers use logging techniques to follow and copy message streams and replay submissions to a participant that unknowingly processes a message as legitimate. Replay attacks are a particular concern for biometric authentication on a client-server architecture. If a successful man-in-the-middle attack is mounted, biometric credentials can be stolen. Unlike password schemes, biometric attributes are not replaceable and revokable. They can be stolen for the life of the victim and reused everywhere those credentials are valid.

Implementing SAASPASS mitigates against replay attacks.