1. A method of generating a cryptographic key for protecting communication between a user equipment and a network entity comprising a mobility management entity, the method comprising, as part of an Authentication and Key Agreement (AKA) procedure initiated by the network entity: obtaining, by a cryptographic key generation device comprised in the user equipment, a Cipher Key (CK) and an Integrity Key (IK); receiving, by the cryptographic key generation device, an authentication token (AUTN) from the network entity, the authentication token (AUTN) comprising an exclusive OR of a sequence number (SQN) and an Anonymity Key (AK); obtaining at least two parameters at the cryptographic key generation device, including a first parameter that comprises or is derived from the Cipher Key (CK) and the Integrity Key (IK), and a second parameter that comprises or is derived from the authentication token (AUTN); and applying, by the cryptographic key generation device, a key derivation function to generate the cryptographic key based on the at least two parameters.