What feature ensures that past communication sessions remain secure even if the network password is compromised?

Forward secrecy is a critical cryptographic feature that enhances the security of communication protocols, particularly in the context of securing past sessions against future compromised keys. This technique ensures that even if an attacker gains access to the current network password or private key, they cannot decrypt past communication sessions. Each session generates unique session keys that are not derived from the long-term secret key, meaning that even if the long-term key is compromised later, previous sessions remain secure because they utilized their distinct keys.

The other options, while they include security measures, do not provide the same level of protection for historical sessions. For instance, MAC address filtering helps control which devices can connect to a network but does not affect the encryption of past communication. Protected management frames focus on securing control messages to prevent certain types of attacks but do not ensure that past data remains confidential if the keys are compromised. Disabling SSID broadcast may enhance privacy by preventing casual discovery of a network but does not influence the encryption of previous sessions. Therefore, forward secrecy is the most effective option for maintaining the security of past communications.