1. A method of generating a cryptographic key for protecting communication between a first entity and a second entity, the method carried out by a cryptographic key generation device comprised in the first entity as part of an Authentication and Key Agreement (AKA) procedure initiated by the second entity and comprising: providing at least two parameters, wherein a first parameter comprises or is derived from a set of cryptographic keys computed by the first entity by running the AKA procedure, and wherein a second parameter comprises or is derived from a token, the token comprising an exclusive OR of a sequence number (SQN) and an Anonymity Key (AK); and applying a key derivation function to generate a cryptographic key based on the provided parameters.