Which of the following keys is derived from a preshared key and Extensible Authentication Protocol (EAP)?

A.
Pairwise Master Key

B.
Group Temporal Key

C.
Private Key

D.
Pairwise Transient Key

Explanation:
Pairwise Master Key (PMK) is the highest order key used within the 802.11i amendment. It is derived directly from a preshared key and can also be derived from the Extensible Authentication Protocol (EAP). It is a cryptography key that is used to derive lower level keys.

Answer B is incorrect. Group Temporal Key (GTK) is a random value that is assigned by the broadcast/multicast source. It is used to protect broadcast/multicast medium access control (MAC) protocol data units. It is derived from a group master key (GMK).

Answer D is incorrect. Pairwise Transient Key (PTK) is a 64-byte key that comprises the following. 16 bytes of EAPOL-Key Confirmation Key (KCK). This key is used to compute MIC on WPA EAPOL Key message. 16 bytes of EAPOL-Key Encryption Key (KEK). AP uses this key to encrypt additional data sent (in the ‘Key
Data’ field) to the client. 16 bytes of Temporal Key (TK). This key is used to encrypt/decrypt unicast data packets. 8 bytes of Michael MIC Authenticator Tx Key. This key is used to compute MIC on unicast data packets transmitted by the AP. 8 bytes of Michael MIC Authenticator Rx Key. This key is used to compute MIC on unicast data packets transmitted by the station. Pairwise Transient Key is derived from the pairwise master key (PMK), Authenticator address (AA), Supplicant address (SPA), Authenticator nonce (A Nonce), and Supplicant nonce (S Nonce) using pseudo-random function (PRF).

Answer C is incorrect. Private Key is not derived from a preshared key and Extensible Authentication Protocol (EAP). This key is used in cryptography techniques.