Comparative Study of Various Security Algorithms Used in Smart Meters

Syed Usman Ali, Essam A. Al-Ammar, Basil AsSadhan, Syed Danish Maqbool

Saudi Aramco Chair in Electrical Power Department of Electrical Engineering, College of Engineering

P.O Box 800, King Saud University Riyadh 11421, Saudi Arabia

{usyed, essam, bsadhan, smaqbool}@ksu.edu.sa

Abstract— With the passage of time and with the dramatic improvements in the field of computers and communications, security gained prime importance especially in the real time and critical environments. Presently, the commonly used meters are electromechanical type based on the rotor element which revolves at a speed proportional to power flow and drives a mechanical registering device on which power consumption is integrated. The output is the sum of all the power consumed during the life time of the meter. This value is read manually by meter-readers, employed by the power companies specifically for this task. These conventional meters are more prone to tempering causing huge monetary loss to the power company. These losses can be reduced by making the monitoring of power consumption easy and free from human error or tempering, by using smart meters. In this article, chaos-based encryption techniques against the traditional or conventional encryption techniques are evaluated based on certain criteria using a MCDM (Multi Criteria Decision Making) tool. Keywords- Security, Smart Meters, Chaos-based, Makeitrational, MCDM

I. INTRODUCTION

In today’s digital world it is imperative to hide and protect critical information from intruders and illicit users. Over the recent decades, researchers and scientists have been trying their best to solve the problem of information security and data hiding, however, these efforts are still incapable of providing a proper encryption technique that can suit all application areas. Recently, problem regarding security has been faced in smart meters, which is one of the most serious issues [1]. A smart meter is a device use to measure electric power consumed. It is used by power companies to keep track of their customers, power usage so that they can be charged accordingly. The idea of a smart meter is technically practical and useful in real world. Smart meters have many advantages over conventional meters since it is based on digital circuits rather than moving parts. Moreover, it has data transmission facility between the consumers and the power company.

This article evaluates chaos-based encryption techniques against the most widely used techniques for encryption i.e. AES and DES. This evaluation is based on certain criteria such as security, integrity, time, computational efficiency, memory requirement, cost, etc. The evaluation process is carried out using MCDM (Multi Criterion Decision Making) tool. The rest of the paper is organized as follows:

Section II consists of a background about the techniques to be evaluated. Section III presents related work conducted in relevant areas. Section IV presents advantages of smart meters over conventional meters. Section V describes the implementation of the proposed work and the results obtained using the MCDM. Finally, section VI concludes the evaluation process.

II. BACKGROUND: CRYPTOGRAPHIC TECHNIQUES

This section briefly elaborates on the cryptographic techniques selected for evaluation.

A. Chaos-based Encryption technique

Chaos means that how simple systems can generate complex behavior and so chaos-based encryption refers to how the encryption and decryption process can be made complicated. Chaos-based encryption is effectively unpredictable because of the sensitivity of its initial condition which means that if slight change is made in the value of initial condition, a significant change will be occurred in the output of the entire process. The idea that chaos can be used in cryptography was given by Claude Shannon in 1950 [2]. After that, the idea was silent till 1980, but soon after 1990 and especially after 2000 the idea began to be recognized and nowadays, it is one of the most widely used techniques for encryption.

B. DES (Data Encryption Standard)

DES was developed by NIST and it has a 64 bit blocks with 64 bit key. The bits of the block are shuffled and XOR’ed with the bits of the key. The entire process is completed in 16 rounds in order to get the cipher text. Same operation is performed for the process of decryption. Many commercial organizations and government institutes used DES because of its ease of code and low computational load [3, 4].

C. AES (Advanced Encryption Standard)

In 1997, the U.S. National Institute of Standards and Technology (NIST) issued a call for a new encryption standard. NIST call the standard the Advanced Encryption Standard (AES). In 2001, NIST selected the encryption algorithm proposed by the two researchers Joan Daemon and Vincent Rijmen from Belgium. The name of their algorithm is Rijindael (from the name of its two inventors) [3, 4]. AES uses much longer keys (128, 192 or 256) and designed especially to resist the most sophisticated attacks such as timing analysis and power analysis.

III. RELATED WORK

The work done by the authors in [5, 6] is relevant to the work presented in this article. Evaluation process for different defense industry frameworks such as Department of Defense Architecture Framework (DoDAF), Ministry of Defense Architecture Framework (MODAF), NATO Architecture Framework (NAF) and Unified Profile for DoDAF/MODAF (UPDM) has been performed. Same multi criteria decision making (MCDM) tool is used in order to carry out the research work.

In the same way, the work done in [7] “Evaluating Encryption Techniques for C4I System” also seems similar. In that paper, the three most widely used encryption techniques, i.e. AES, RSA and Quantum encryption are evaluated. The similar methodology was used in order to select the best encryption technique for C4I system. The tool that have used is different from the one that is being used here.

IV. ADVANTAGES OF SMART METERS OVER

CONVENTIONAL METERS

Conventional meters are more prone to tampering as compared to smart meters; this is because conventional meters can be simply tampered by adjusting the distance between the rotating disk and the damping magnet, thus reducing the speed of rotation of the disk [8]. Tampering smart meters, on the other hand would require either reprogramming the device or replacing some components, which is difficult.

The smart meter does not involve any moving parts, thus it does not suffer from any mechanical wear and tear and remains consistent and accurate throughout its life time.

Due to the digital circuitry, smart meters have the flexibility to change. To add new functions, all that has to be done is to change the software or interface new digital hardware.

Integrated circuits are getting cheaper and cheaper day by day, industrial production of smart meters will be more economic than conventional meters. Since the data is available in the digital storage, it can be transmitted through various means (e.g., through power line carrier or through radio transmitter) to the central billing station. Thus the meter will also save labor cost during its lifetime by replacing a meter-reader [9].

Smart meter-reading provides increased performance in the data collection; avoids reading errors and missing meter readings. Reading the data automatically also provides increased security of data flow between the AMM (Automated Meter Management) system and other applications. This leads to avoiding manual data entry or manual data transfer, which is a potential source of errors.

V. IMPLEMENTATION

The comparative study done is this paper of various security algorithm used in smart meters is carried out by using the MakeItRational tool. MakeItRational is a decision making tool that draws the result based on certain steps. The main decision factors are; goal selection, alternatives, criteria, sub-criteria, preference and finally results. Fig. 1 shows the main

hierarchical diagram of the entire process. The description about each step is given below.

Figure 1. Block diagram of the hierarchical process

We explain each step of this process below.

A. Goal Selection

This part is concerned with the selection of goals. The main goal in this case is to compare Chaos-based against AES and DES techniques and to come up with a conclusion which technique is more appropriate for the securing smart meters communications.

B. Alternatives

This portion is concerned with the main alternatives that are being to evaluate. In this case the three main alternatives are summarized in Table I.

TABLE I. MAIN ALTERNATIVES

Number Name

1 Chaos-based Encryption techniques

2 Advanced Encryption Standard

3 Data Encryption Standard

C. Main Criteria

Seven main criteria have been identified based on which, the encryption techniques are evaluated. The identified criteria include: security, integrity, flexibility, availability, time, cost and robustness. Additionally, the criteria are decomposed into sub-criteria. For instance, the "security" criterion is decomposed into the sub-criteria "actual security" and "soundness". Similarly, the "flexibility" criterion consists of “suitability” and “simplicity”. The "time" criterion has two sub-criteria: "encryption time" and "decryption time".

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D. Preferences

Preferences concerned with the assignments of priorities. Priorities are assigned based on Table II.

TABLE II. PRIORITIES WITH THEIR IMPORTANCE

Intensity Importance 1 Equal Importance

2 Weak Importance

3 Moderate Importance

4 Moderate Importance plus

5 Strong Importance

6 Strong Importance plus

7 Very Strong Importance

8 Very Strong Importance plus

9 Extreme Importance

The details about each preference assigned to each criterion and sub-criterion are summarized in Table III.

TABLE III. PREFERENCES WITH THEIR RATIO OF IMPORTANCE

Criteria Ratio Security vs. Robustness 4:1

Integrity vs. Robustness 2:1

Security vs. Integrity 3:1

Security vs. Flexibility 3:1

Security vs. Availability 4:1

Security vs. Time 3:1

Security vs. Cost 3:1

Integrity vs. Flexibility 2:1

Integrity vs. Availability 3:1

Time vs. Integrity 3:1

Cost vs. Integrity 3:1

Availability vs. Flexibility 3:1

Time vs. Flexibility 3:1

Cost vs. Flexibility 3:1

Flexibility vs. Robustness 2:1

Time vs. Availability 3:1

Cost vs. Availability 3:1

Availability vs. Robustness 2:1

Time vs. Cost 3:1

Time vs. Robustness 2:1

Cost vs. Robustness 4:1

Security vs. Robustness 4:1

E. Results

This section consists of several-graphs illustrating the overall results of the evaluation process. From these graphs, a number of conclusions are drawn.

Figure 2. Alternatives ranking

The graph in Fig. 2 shows the ranking of alternatives according to their importance and severity. Like in AES, security is more important issue than the others, but in Chaos-based encryption techniques integrity and cost is more important. In other words, it can be said that in terms of security, AES is the best option. However, in terms of integrity and cost, chaos-based encryption techniques are the best option for smart meters.

Figure 3. Alternatives Comparison

The graph in Fig. 3 illustrates the comparison of alternatives. So if the following criteria are more important for the operation of smart meters: availability, cost, flexibility, integrity and robustness, then chaos-based encryption

techniques are the best option. But if time or securities are more important, then AES is the best option to use.

Figure 4. Alternatives weights

Similarly the graph in Fig. 4 shows the importance and severity of each alternative or criterion. It can be seen that security has a value of about 33%, which means that security is one of the most important issue that must be considered in order to evaluate the encryption techniques. Moreover time is also an important issue that must be considered in order to evaluate the various techniques. The details about some of the criterions along with their graphical representation are given below.

F. Integrity

Integrity is concerned with the protection of information and data from damage or deliberate manipulation. In other words, it is the property that ensures that data has not been modified. Table IV summarizes the integrity along with their preference assigned to each main alternative used in the process of evaluation.

TABLE IV. PREFERENCE ASSIGNED TO CRITERIA INTEGRITY

Alternative Preference ration

Choas-based Encryption tech vs. Advanced Encryption Standard

4:1

Advanced Encryption Standard vs. Data Encryption Standard

3:1

Choas-based Encryption tech vs. Data Encryption Standard

5:1

The table shows that chaos-based encryption has moderate importance plus against the AES. Similarly AES has moderate importance against DES, while Chaos-based encryption has strong importance against DES. The priorities or importance of criteria is assigned according to Table II.

The graph shown in Fig. 5 depicts the importance of integrity in each alternative. For example chaos-based encryption has an integrity value of 67% with respect to AES and DES. Similarly AES has an importance of 23% with respect to DES and chaos-based, while DES has a value of 10% with respect to AES and chaos-based. From the above

statistics it is clear that chaos-based encryption has a better integrity ratio than the two others.

Figure 5. Alternative utility

G. Time

This is basically the time taken by an algorithm to encrypt or decrypt data or information. From the literature review, it is clear that chaos-based algorithms take less time than AES and DES in order to encrypt or decrypt data. Also the graph given in Fig. 6 shows the same statistics.

Figure 6. Alternative utility

The Fig. 6 shows the percent time taken by each alternative for the entire process. For example, AES takes about 30% time for the encryption or decryption. Similarly DES takes 15%

time for the same process, while Chaos-based algorithms take 7-8% time in order to encrypt or decrypt the same data. This shows that chaos-based encryption techniques are more appropriate for the process of encryption and decryption in the case of smart meters.

H. Security

Security refers to the protection of information in hostile environments. The security of a cryptographic algorithm depends on the two factors: actual security and soundness. Actual security is concerned with the key and block size of the algorithm, while soundness is the mathematical property of the algorithm used for the purpose of security. The detail graph about the sub-criterion of security is given here.

The graph in Fig. 7 shows the ratio of actual security and soundness in all three alternatives. AES provides more security than chaos-based and DES. Similarly chaos-based provides more security than DES. From this graph, it is clear that AES is one of the most appropriate algorithms that can be used in smart meters high preference is given to security.

VII. REFERENCES

[1] R. Berthier, W. H. Sanders, and H. Khurana, Intrusion Detection for

Advanced Metering Infrastructures: Requirements and Architectural Directions," in 2010 First IEEE International Conference on Smart Grid Communications, 2010, pp. 350-355.

[2] Rincu. Cristian-Iulian, Serbanescu. Alexandru,”Chaos-based Cryptography. A possible solution for information security”, Bulletin of the Transilvania University of Brasov, Volume 2(51), series III, Mathematics, Informatics and Physics, pp: 113-126, 2009.

[3] William Stalling, "Cryptography and Network Security", 4th Edition.

[4] Morkel T., Eloff JHP, "Encryption Techniques: A Timeline Approach", Information and Computer Security Architecture (ICSA) Research Group, Department of Computer Science, University of Pretoria, 0002, Pretoria,SouthAfrica.

[5] Abdullah S. Alghamdi, Iftikhar Ahmad, “Comparative Analysis of Defense Industry Frameworks for C4I System”, IEEE 2nd International Conference on Computer Engineering and Applications ICCEA 2010, Bali Island, Indonesia, March 19 - 21, 2010, pp. 443-447.

[6] Abdullah S. Alghamdi, “A Review of Commercial Related Architecture Frameworks and their Feasibility to C4I System” European Journal of Scientific Research, ISSN 1450-216X Vol.40 No.1 (2010), pp.43 -49.

[7] Abdullah Sharaf Alghamdi, Hanif Ullah, Iftikhar Ahmad, “Evaluating Encryption Techniques For C4I System”, Computer Applications in Industry and Engineering (CAINE-2010), 23rd Int'l. Conference November 8-10, 2010, Las Vegas, Nevada, USA.

[8] R. Gerwen, S. Jaarsma, and R. Wilhite, “Smart metering,” [Online].Available: http://www.leonardo-energy.org/webfm_ send/435.

[9] Jos Hessels. CDA. In Energie Metering & Billing. Institute for International Research, 06, 2008.

Figure 7. Alternative utility

VI. CONCLUSION

Based on the information presented in this paper, it can be concluded that Chaos-based encryption techniques are more appropriate in order to provide high level of security to the smart meters based on certain criteria. But if other criteria like security and time are considered then AES is the best option to be used for the encryption of data and information in the smart meters. The result will help researchers and engineers to select the most efficient and most secure method for implementation while designing smart meters.