Today’s electrical grid is changing rapidly into a smarter grid to address the demands of distributed generation. An important task for the smart grid is accurate monitoring of energy consumption and production. Smart metering is a crucial part for the realization of the vision of smart grid. In its most basic form, it describes a deployment of electric meters that enable two-way communication between meter and distribution system operator. This is often called the Advanced Metering Infrastructure (AMI).

Smart metering provides accurate, near real-time measurements of household consumption. Using this data, energy suppliers can plan their energy production more efficiently and provide users with real-time pricing. However, smart metering data also poses a threat to the privacy of people living in the measured households. Using nonintrusive load monitoring, anyone with access to smart metering data can deduce highly private information [1] [2]. Even with measurements taken only every 15 minutes, patterns of usage for appliances can be deduced. Private information like working hours, personal habits and even religious beliefs are at risk of being no longer private through smart metering [3].

At present, extensive studies have been conducted on the information security of smart grid [4] [5] [6] [7]. However, most of the results achieved are not applicable to the privacy problems of the smart electricity meters. In this paper, we propose a security and privacy-preserving metering scheme for the community customers, by utilizing the password authenticated key exchange (PAKE) protocol [8] [9] [10] and Elliptic Curve Cryptosystem (ECC) [11] [12] [13]. The rest of this paper is organized as follows: Section 2 presents the related background knowledge. Section 3 describes our proposed scheme while its security analysis and algorithm comparison are proved in Section 4. Finally, Section 5 concludes the paper.

To authenticate mutually network devices in the energy community, an enhanced ECC based password authentication scheme in is utilized. As shown in Figure 3. To ensure the reliability and confidentiality of data transferring, the mutual authentication between community energy management systems and smart meters is necessary. As shown in Figure 3, after a secure session has been established, the community user data can be gathered in hidden way, and the aggregated data is the total consumption of the community electricity, attacker can’t get user’s personal consumption data to pry user’s privacy.

More specifically, this proposed scheme is divided into three stages: initialization phase, authentication phase, data privacy phase, which are described as follows.

In this section, the security of proposed protocol is analyzed and it is shown that the proposed scheme has resilience to several well-known attacks, such as replay attack, dictionary attack and man-in the middle attack. Here, we briefly explain the security properties for the proposed protocol.

Known session key security: The session keys of different sessions are independent from each other, and it is difficult for attackers to acquire a new session key from the revealed session keys of the past sessions. Because the session key is calculated from two random numbers and that are independently selected by Community EMS A and smart meter B, respectively. These random numbers will change for every session. Therefore, the proposed protocol provides the known session key security properties.

The current session key security: In the security authentication stage, the selection of random number, and generation of session key occur inside their own devices of both parties without transmitting through the wireless channel, the attacker can’t steal Meaningful results. In addition, because of the collision-resistant property of a one-way hash function, adversary can’t obtain from the equation.

Resilience to dictionary attack: In the authentication phase between CEMS and smart meters, the password information Pw shared between the two sides does not appear in the transmission process, an attacker can’t get a clear confirmation of the password. Assuming that the adversary guesses as a password of smart meter, but he/she does not have the pre-shared secret key x, so he/she cannot compute the expected values. Therefore, A cannot acquire the correct value and obtains a different value and validates. Obviously, A recognizes that the opposite party is not the real one, the attack take places and then A stops protocol run with error, so the attack on password is discernible.

Resilience to password compromised impersonation attack: It is assumed that the smart meter’s password Pw leaks, the attacker knows Pw, but doesn’t aware the pre-shared keys x, the correct π is still unknown. Thus the check fails and the attack cannot be carried out. Moreover, even if calibration is successful, and get the right from equation, the attacker cannot get the selected random number from formula because of the difficulty of solving ECDLP. Consequently, the password compromise impersonation attack cannot take place on the proposed protocol.

Resilience to illegal devices masquerading attack: Each device in the network has its unique ID, before the authentication phase, all smart meter ID’s hash value will be stored in the database of the trusted center. If an attacker with illegal equipment want to camouflage smart meter to communicate with CEMS, he/she need to send the device ID of the hash function H(ID) to a trusted center to check first. If no hash function satisfies the requirement, the protocol can be stopped.

Resilience to replay attack: In this protocol, Two random numbers and generated from A and B separately are used in constructing the session key and other factors. The selection of random number ensures the novelty of session, and guarantees us that the proposed scheme is secure against replay attack.

Resilience to key compromise impersonation attack: Suppose that private key of energy management system compromises, the attacker still cannot get the correct session key. Because the attacker does not know the random number EMS selected, and also can’t get the corresponding password Pw and pre distribution key x from the smart meter, unable to get the correct from the. Therefore, the correct session key is not calculated. Similarly, even if the smart meter’s private key leaks, the results also cannot solve the correct session key.

Privacy preserving: This scheme adopts the way of adding shielding parameters, hiding the real power data of the users, and cannot get the valid data from the users, user’s actual energy consumption is only in the community energy management system, nor can it be a threat to the user’s behavior and the stability of the power grid.

In this paper, the password authentication and elliptic curve cryptography are combined to realize the two-way secure authentication between smart meter and community energy management system in energy community. Under the premise of ensuring the security, reliability and non-repudiation of communication, the user’s privacy is protected. The security of the ECC based password authentication algorithm is better under the condition of the same key length because of the particularity of the short distance wireless communication. Compared with other encryption algorithm, elliptic curve cryptography (ECC) has great advantages in computational demand, key length and security, especially suitable for resource constrained environment. Due to the intractability of the elliptic curve discrete logarithm problem, the protocol can effectively resist the impersonation attack, replay attack, password compromise impersonation attack, dictionary attack etc.

Sun, Z.W. and Song, C.Q. (2017) Security and Privacy-Pre- serving Metering Service in the Smart Grid. Int. J. Communications, Network and System Sciences, 10, 307-315. https://doi.org/10.4236/ijcns.2017.108B033