Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a relay UE, a first message comprising a first freshness parameter, an identity of the UE, and authentication information, where the authentication information is used by a network node to authenticate the UE with security context information of the UE. The UE may derive a relay key for security establishment between the UE and the relay UE based on the first freshness parameter, a set of key generation parameters, and a shared key with the network node. The UE may derive a relay session key for security establishment between the UE and the relay UE based on the relay key, a first nonce of the UE, and a second nonce of the relay UE. Numerous other aspects are described.