Replay attack protection is the prevention of an attacker resending a previously valid request or message to trigger unauthorized repeated effects. It matters because a message can remain dangerous even if it was authentic the first time.
What is Replay Attack Protection?
Protection often uses nonces, timestamps, sequence checks, short-lived signatures, or idempotency controls. It matters in APIs, webhooks, payment flows, and signed requests where the attacker may capture and reuse valid traffic.
What Replay Attack Protection Commonly Supports
Common uses include webhook defense, API request security, payment protection, and message integrity design.
Replay Attack Protection vs. Single-Use-Blind Request Validation
Replay protection checks whether a valid message is being reused outside its intended one-time context. Blind validation only checks whether the message looks authentic.
Frequently Asked Questions
Why is replay protection needed if requests are signed?
Because a correctly signed request can still be abused if it remains reusable.
What commonly helps prevent replay?
Timestamps, expirations, nonces, and idempotency handling are common controls.
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