Key Management for Group Software Distribution. With particular reference to the SEGRID use case 1[5], one Data Concentrator device and a number of associated Smart Meter devices can be intended and configured as members of a same group. Among other tasks such as collecting measurements from and issuing commands to the Smart Meters in the group, the Data Concentrator is responsible for distributing software updates (e.g. new firmware versions) to the Smart Meters. This operation can be efficiently performed via multicast communication within the group. In this way, a reduced amount of information has to be transmitted and the update process can be completed in a shorter time. Nonetheless, it is necessary to secure the software update process by encrypting communication within the group. This is vital in order to prevent an external adversary from collecting the distributed software updates, analysing and/or reverse-engineering them, and possibly finding vulnerabilities that can be exploited to mount cyber-attacks against Smart Meter devices. In order to provide secure communication within the group, the software distribution process must rely on some cryptographic key material. However, this results in the additional task to properly and securely manage the key material itself, i.e. revoking and re-distributing it in a secure and effective way upon the occurrence of specific events. In addition, this key manage- ment process is required to be efficient and scalable with the number of devices in the group, as well as to display a limited and affordable impact on network and system performance. XXXXXX developed a solution for ‘Key management for group software distribution’, applying a novel group key management protocol. It is highly scalable and has efficient collusion recov- ery procedures.
Key Management for Group Software Distribution. In order to achieve high scalability and performance, a single Smart Data Concentrator can send software updates to multiple associated Smart Meters at once, by means of multicast group communication. Such communications are secured by using a commonly shared group key. Upon a number of events, the group key must be revoked and renewed. Until this operation is successfully completed, secure group communication between the Smart Data Concentrator and the associated Smart Meters must be suspended. The proposed solution developed in SEGRID is extremely efficient and highly scalable with the number of Smart Meters considered in the same group. Therefore, unlike with alternative approaches, it is possible to fully restore secure communication within the group in a shorter amount of time, and more efficiently for Smart Meters from a performance point of view. The gain in time to process the change of a former broadcast key to a new one, and the fact that the amount of exchanged messages is less than for other former approaches, make the chance for an attacker to take advantage of the compromised nodes, whilst there is a change in broadcast key, to diminish dramatically. Then, by reducing the amount of time required to fully restore security in the group, the SEGRID security solution reduces the risk that:
