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Question 463

A security administrator wants to enable a feature that would prevent a compromised encryption key from being used to decrypt all the VPN traffic. Which of the following should the security administrator use?

    Correct Answer: D

    Perfect forward secrecy (PFS) ensures that session keys are uniquely generated for each session and not derived from any long-term key. If an encryption key is compromised, it cannot be used to decrypt previous sessions, as those keys are not related to the compromised key. This feature is crucial in protecting past communication if a key is compromised in the future, making it the ideal solution for the security administrator's requirement.

Discussion
isaphiltrickOption: D

Perfect forward secrecy (PFS) is a feature in cryptographic systems that ensures that session keys derived from long-term keys are not compromised even if the long-term keys are compromised in the future. In the context of VPNs, PFS ensures that each session key used for encryption is unique to that session and not derived from the VPN server's long-term private key alone. This means that if an attacker obtains the server's private key later on, they cannot use it to decrypt past VPN sessions because those session keys were derived separately and are not accessible from the compromised private key. Thus, PFS protects VPN traffic from retrospective decryption by ensuring that compromise of a long-term key does not compromise past session keys.