In our webcast Creating a Platform of Trust-Meter Data Transmission The Secure Way, Philip Mason, Senior Product Manager, Smart Energy Solutions, EMEA, Landis+Gyr, discusses how a flexible and multi-layered platform can enhance the security of a smart metering system.
There are a number of drivers for secure smart metering systems. Suppliers want to ensure the availability, reliability and security of energy supplies. They also want to comply with regulations and reduce business risks.
Utilities also need to take into account that while customers expect reliable power, they also expect their personal information, collected by the smart meter, to be protected.
Regulation - a primary driver for secure smart metering systems
The EU Regulatory environment for smart meter security and privacy
A country’s regulations can have a major driving effect for smart meter security systems. There are there very relevant publications coming out of the European Union:
EU Recommendation 2012/148/EU- This lays out the preparations for the roll out of smart metering systems. It states that Directives 95/46/EC and 2002/58/EC are fully applicable to smart metering which processes personal data, in particular in the use of publicly available electronic communications services. Data protection and information security features should be built into smart metering systems before they are rolled out. Also, the use of encrypted channels is recommended.
Directive 95/46/EU-(known as the Privacy Directive)-This points to the protection of individuals with regards to the processing of personal data and on the free movement of this data. The directive describes personal data as “any information relating to an identified or identifiable natural person.” The processing of personal data is described as “any operation or set of operations which is performed upon personal data, whether or not by automatic means such as collection, recording, storage …disclosure by transmission,…”
Directive 2002/58/EC-The processing of personal data and the protection of privacy in the electronic communications sector. The directive points out that service providers should take appropriate measures to safeguard the security of their services. It states that measures should be taken to prevent unauthorized access to communications in order to protect the confidentiality of communications.
It is very clear what needs to be achieved through these regulations and it is therefore vitally important that utilities in the European Union comply with these.
Unfortunately, in the European Union, the single approach on smart metering security has yet to be developed. The barriers to this approach are as follows:
Different security architectures have been proposed by France, Germany, Netherlands, Spain and the UK. They are all achieving the roll-out and security goals as set out by the directives but they are all doing it in slightly different ways
There is a broad European landscape of national and industry security guidelines. The onus is on individual manufacturers to prove the capability of their systems as there is no specific guidance coming out of regulation.
It is a slow and loosely coordinated path to European standardization and regulation as there is not a very strong appetite in Europe to create a single set of regulations for smart metering security. This is probably because security is considered by governments to be of national interest and security may be used to protect markets.
The US federal government drives a centralized approach. This has been published in the form of a document by NIST (National Institute of Standards and Technology). The institute developed NISTIR 7628- a National Institute of Standards and Technology Interagency Report. It is a very relevant set of documents laying out the benchmark for activity in the area of smart grid cyber security. It is wide ranging and influential-a document that Europe will find useful as it can be used as a guideline for the future with regards to smart meter and security development.
Achieving interoperability in smart meter communications security
Interoperability is when systems can be built up with components and devices from different suppliers. These can then be interchanged with no change or loss in functionality.
This is important for utilities as it gives them flexibility in the way they purchase their system components. In addition, they can split sourcing. Utilities will be given the flexibility to install meters and system components from various suppliers and be certain that they will work side-by-side in the smart metering system.
Obviously, this interoperability calls for security across all systems.
There are currently two associations that are driving smart meter interoperability:
DLMS-COSEM (Device Language Message Specification-Companion Specification for Energy Metering IEC62056)
IDS-Interoperable Device Interface Specifications
Interoperable secure communications verified by IDIS
Available standards don’t cover interoperability sufficiently-they can leave a lot of room for interpretation. It is quite common for two different types of products, made according to the same standards, not to be interoperable because of the difference in interpretation or the different choice of variables.
What is required on top of the standards to create an interoperable platform is a companion specification. This creates a platform of shared understanding:
1.Basic connectivity-physical and logical connection
2.Network interoperability-exchange of messages via different networks
3.Syntactic interoperability-understanding of data structures in the messages
4.Semantic interoperability-understanding of concepts contained in the data structures
To create a platform of interoperability, you have to :
Select appropriate standards
Select options-The utility needs to decide which part of the standards they will be using and which values are going to be set for the variables. The decisions have to be unanimous.
Prove that interoperability has been achieved-A test for conformance should be carried out. This sounds easy but someone has to take responsibility for that and it is normally undertaken by IDIS.
IDIS, built on DLMS authentication and encryption security, supports multiple transport layers.
There are currently 11 transport technologies:
PLC PRIME OFDM
PLC G3 OFDM
RF IP v4-v6
GPRS 4G IP v4-v6
These are being brought under the umbrella of IDIS. Any of these devices (even using different transport layers) are all covered at the DLMS application layer and the COSEM Data Model layer. They will all use a common application layer for process and encryption (DLMS authentication and Encryption). This provides a very “future ready” technology regardless of which transport layer will be used. They all use the same authentication layer.
How using encrypted and authenticated messaging builds trust
When it comes to security, trust must be built. This can be done by ensuring:
Message confidentiality–Disclose information only to authorized entities.
Message integrity-Do not allow information to be changed.
Message authenticity-Show information only to entities whose right of access has been verified
These aspects are guaranteed to create a trustworthy system.
The communication aspect of smart metering systems
Confidentiality and integrity is guaranteed in cryptography by using ciphered messages. Authenticity can be guaranteed using an authentication tag, created through an authentication key. Companies can also make use of secure key distribution-the key is wrapped with MasterKey.
The basic functionality of DLMS creates trustworthiness. DLMS message cryptography-DLMS uses AES-GCM-128 (advanced encryption standard, galois counter mode, 128-bit key lengths-is made up of multiple symmetric keys that have different functions in the system-
Unicast encryption key
Broadcast encryption key
Key encryption key
Each of these keys have a specific purpose in the protocol. When information is sent from the meter to the receiver, the DLMS packet draws on the AES-GCM-128 galois counter mode for authenticated encryption. First, it will create a “header” for the message length. Then, a tag is added to say there is an encrypted message (authenticated encryption). After that, an initialization vector (IV) is needed.
This is made up of a frame counter so the system takes the frame counter which is applicable for this message from sender to receiver and then adds this to the system title, (a unique serial number). Then, the plain text is changed into cipher text.
The encryption key will take the plain text and turn it into an encrypted message. The authentication key then authenticates the message. The authentication key is added to the plain text data which creates an authentication tag (attached to message). A ciphered DLMS packet has now been created. The content has been encrypted and authenticated. This is then sent to the receiver.
The receiver is of course running the same algorithm to decrypt the message using the AES-GCM-128 galois counter mode for authenticated decryption. The system compares its own frame counter with the incoming frame counter to ensure that the message has not been diverted through an unauthorized third party. It then adds its own system title. The initialization vector which is being built in the receiver should be identical with the initialization vector which was built at the sender’s system. If this is not the case, an error message will come up immediately.
Once the message has been authenticated, the authentication tag will be decrypted and will be checked for its authenticity. Finally the text is decrypted and is combined with incoming cipher text. The system then “spits out” the restored DLMS packet.
This method can be trusted and is highly reliable, says Mr Mason.
Gridstream secure communications implementation
The Gridstream solution, discussed during the webcast, is sold in Europe, Middle East and Africa.
Gridstream is Landis+Gyr’s integrated smart metering platform. It combines energy measurement devices, communications infrastructure (including mobile and powerline communications and data concentrators), software applications and professional services for the rollout operation and maintenance.
About the Gridstream system:
Technology is driven by IDIS industry association as Landis+Gyr believes in the benefits of system and security interoperability
The underlying technology is from DLMS (which is the symmetric key system) It is an appropriate technology for this environment.
DLMS is applied to power line and mobile communications
For those parts of the system that are not covered by DLMS, TLS tunnel to data concentrator is employed
The system uses a “Secure Key Manager”/ “Hardware Security Module” for crypto-management
Initial key generation is used
The smart metering concept has specific characteristics which influences the choice of technology for security:
The communications bandwidth (which is used over the power line channels) is relatively low-of the order of a few kbit/s. It is important that algorithms are efficient and don’t have a lot of transmission overhead.
Meters have a limited processing capacity (they are not smart phones!)
The number of meters in customer rollouts varies widely (over a range of approx. 10k-10m devices). It is important that every solution scales well.
Technology suited to smart metering
DLMS cryptography is appropriate for securing communication with smart meters:
Application layer cryptography works with many transport layers
The processing capacity necessary for GCM-AES-128 symmetric key algorithms is low, particularly when compared to asymmetric key algorithms
Adds only a small protocol overhead for encryption/authentication-less than 10% compared to no encryption/authentication
Unique set of keys per meter protects against system wide attacks
Excellent scalability: The amount of computing resources necessary for operational key management in the head end system is independent of the number of meters, a single Hardware Security Module can serve millions of meters.
Why use a Hardware Security Module?
Offers the highest level of protection for root cryptographic assets (this kind of protection is not available in software)
True random number generation for initializing key creation algorithms (using physical processes to get random numbers)
Highest level of tamper resistance and physical security
Most reliable storage, fail-over and disaster recovery, and offers significant resilience
The availability of keys can be guaranteed with a resilient infrastructure. Landis+Gyr works with Safenet Incorporated for this type of security technology.
Connected to the head-end system would be :
1.The hardware security module which takes care of the route assets
2.Many systems would use the Hot Fail-Over Mirrored pair on-site
3. For floods and similar disasters, Landis+Gyr recommends the disaster recovery back-up unit off-site.
The foundations of a secure communication system can be traced back to highly reliable and highly secure devices which are an integral part of a security system, explains Mr Mason.
Gridstream symmetric key cryptography
This is used between the DLMS server and the client:
-Meter to data concentrator (power line)
-Meter to head end system (mobile)
Each meter uses a unique set of keys which means that the meter, data concentrator and the head end system share the same keys. Replacement keys are distributed securely and keys are stored securely.
Gridstream asymmetric key cryptography
The challenge of any asymmetric key system is getting the keys in the right place. To do this, Landis+Gyr employ asymmetric key cryptography. When transferring keys from the Landis+Gyr manufacturing facility to the operative head-end system, there is an asymmetric process based on top of a public key infrastructure. The company uses asymmetric key cryptography certification when it comes to field access tools. The company also uses it to get information from data concentrators to the head end system.
Gridstream key distribution
Symmetric key cryptography is used for meter data. The meter and the head end system need to use identical keys. A set of initial keys are written into the meter at production and a set of identical keys are sent securely from the production facility to the customer’s head end system where they are stored securely.
Gridstream secure deployment
Landis+Gyr write initial keys into the meter-the company’s production system then sets up a secure communication system with the customer.
The initial keys are then sent to the utility (information is sent in the form of a key file). This is encrypted and authenticated. Keys are then stored in the head end system (using the hardware security module).
In the interim, in the field, meters are being installed and access to the meter is secured using the field tools.
This now enables secure messages using high level security and encryption thanks to IDIS DLMS-COSEM high level security authentication and encryption
Secure communications in smart metering systems doesn’t mean manufacturing smart meters with keys in them, it means setting up an entire chain of trust through the communications infrastructure, up into the head-end system. It also includes having a chain of trust back to the manufacturing environment. The only way to do that is to have a single system like Gridstream, says Mr Mason.
Benefits of secure communications
Multiple layers (authentication and encryption) and flexibility to change the keys is what makes this system more robust than others, explains Mr Mason. Because each meter has a unique set of keys, one “hacked” meter will not affect the others since hacking will be isolated.
Ensures power availability-Enhanced security systems will reduce the risk of supply disruption caused by malicious attack over smart meter communication channels
Compliance with privacy regulations-Ensures the confidentiality of consumer energy measurement data between the head end system and meter
Protects assets-Prevents malicious damage to smart meter infrastructure caused by unauthorized devices
Reduces risk-Reduces exposure to business risk due to compromised privacy, network cyber-attack, and energy theft.
Creating a Platform of Trust-Meter Data Transmission The Secure Way “Security is a never-ending story. You are always trying to stay a few steps ahead. With this system, we feel we are in good shape.” Philip Mason, Senior Product Manager, Smart Energy Solutions, EMEA, Landis+Gyr.