Patent ID: 11616646

Abstract:
A method for replacing an existing key derivation key in a utility meter arranged in a meter communication infrastructure in a secure way. The method provide a secure mechanism for exchange of symmetric keys without the need for transferring keys across the meter communication infrastructure. From the head-end system to the utility meter is transmitted a command data message comprising a request for replacing the existing key derivation key with the new key derivation key, the key-generation information and a activation key or an authentication code calculated based on the activation key. The utility meter receiving the command data message is arranged to derive the new key derivation key based on a copy of a disaster recovery key stored in the utility meter and on the key-generation information comprised in the received command data message. Further, the utility meter is arranged for deriving a activation key from the new key derivation key. The activation key is used for verifying the command data message. If the command data message is verified the existing key derivation key is replaced by a new key derivation key.