Certified Ethical Hacker (CEH) Practice Question

A replay attack succeeds because the protocol accepts previously used ciphertext as valid. Introducing a unique, unpredictable value-such as a cryptographically secure random nonce or timestamp-into each challenge ensures that every authentication exchange is unique and can be accepted only once. Even if an attacker records the traffic, the reused message will be rejected because the server expects a fresh nonce. Simply lengthening the key, base64-encoding, or compressing the data does not prevent an attacker from resending a valid prior ciphertext; the underlying vulnerability is the absence of freshness verification, not insufficient key size or data formatting.