Reuse of previously observed valid messages to obtain an acceptance or action in a different context. Cryptographic nonces, fresh session keys and explicit context binding can prevent particular replay patterns.
Obtaining valid responses to a predicted future challenge before that challenge is issued, then delivering them when the predicted value becomes current. Challenge uniqueness alone need not establish freshness when challenges are predictable.
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A replay attack is a type of network attack where an unauthorized party intercepts and captures a valid data transmission (such as a login request or a financial transaction) and then retransmits that data to deceive the system into thinking that it is a legitimate request. The attacker aims to gain unauthorized access, repeat transactions, or otherwise exploit the communication for malicious purposes. ### Key Characteristics of Replay Attacks: 1. **Interception**: The attacker must first intercept the original data being transmitted over a network.