Research Issues Related to Cryptography Algorithms and Key Generation for Smart Grid: A Survey Ajay Kumar Electronics and Communication Department Thapar University, Patiala, India. email@example.com Abstract- With advent of technology existing electrical grids are changed to smart grids which are effective power management, secure communication, reduced production cost and environment friendly. But, Smart Grid is complex hierarchy architecture. There are various stakeholders included. So, the biggest challenges are authentication and authorization. Secondly how to secure the communication lines from various cyber attacks. In this paper, a survey is done on various cryptography algorithms and related key generation for smart grid application. On the basis of survey several research issue have been discussed for the secure operations in the smart grids. It has been found that lightweight algorithms are more suitable in smart meters because of less area and memory required. Key generation for cryptography algorithm should be generated from noise and jitter as a seed because of their random nature to prevent from cyber attacks. Keywords-Cryptography, Smart Meters, grids, cyber attack and security. I. INTRODUCTION In last few years due to load unbalancing there is a blackout of electricity industry and due to users affected and wastage of money. Smart Grid is the next generation of power grids because it provides an effective two way communication between users and supplier. Alpana Agarwal Electronics and Communication Department Thapar University, Patiala, India. firstname.lastname@example.org Smart grid includes various kinds of sensors in smart meter which provide user’s real time electricity usage and manage and give instruction from central unit. Also, smart meter provides efficient power management, better reliability, balance between generation and consumption . 1.1 Overview of Smart Grids Architecture Fig. 1 shows the Smart Grid is a hierarchy in which at the bottom layer Home Area Network (HAN), Building Area Network (BAN), and Industrial Area Network (IAN) involved and which are either wire or wireless connected with smart meter. Smart meter are responsible for giving users electricity usage reports to grids. The middle layer include Neighborhood Area Network which combine the small geographic area smart meters and responsible for the different distributions. The upper most layer, monitor and manage electricity .In monitoring they check the load balancing on the transmission lines so load unbalancing never occur and also according to environment takes action. In management according to demand they forecast their future plan for electricity generation. Also generate electricity bills according to user’s electricity usage. 1.2 Different Communication Attacks in Smart Grids In communication system the attacks are categorized in two parts . 1.2.1. Passive Attacks: In general, when two parties are communicated third party silently listening your message without affecting your system resources. In smart grids, the passive attacks are take form of Eavesdropping or Traffic Analysis. The Eavesdropping refers to unauthorized inception of an on-going communication without the permission of the communicating parties. On the other hand in traffic analysis the unauthorized parties are monitoring of your electricity loads information for some physical attacks. For example, in smart grids within every 15 minutes the customer electricity traffic load are communicated to local substation using smart meters. So from traffic analysis the unauthorized parties know when you come home and go for office. Fig 1. Multilayer Architecture for Smart Grids  978-1-5090-4530-3/16/$31.00 ©2016 IEEE 1.2.2. Active Attacks: In active attacks, the unauthorized parties are according to their requirement can modify messages or harm the system resources when two parties are communicating. In smart grids, these unauthorized parties are tries to pass some wrong information to smart grids so they take some wrong actions and due to load unbalancing or black out of electricity. 1.3 Design goals for Smart Grids Due to different types of attacks, some design goals are adopted for smart grids security. These are a) Confidential Table 1: Comparative Analysis between Symmetric and Asymmetric Algorithm Symmetric Algorithm used for decryption Different keys are used for encryption and decryption purposes. Symmetric algorithms are used for plaintext encryption. Asymmetric algorithms are used for authentication purposes. Key is shared with cipher text on the network for decryption purposes. No need communication. Same key is encryption and purposes b) Authorization c) Integrity d) Availability e) Non Repudiation f) Authenticity 1.4 Overview of Cryptography Algorithms in Smart grids Smart grid is complex hierarchy architecture and various vendors are included. So authenticity and authorization is a big challenge in Smart Grids. To fulfill the design goals of smart grid different cryptography algorithms are used for secure communication. In Cryptography the message write in such a notation only communicating parties knows how the data is encrypted. Fig.2 shows the basic block diagram of cryptography. In Cryptography in which some random key and encryption algorithm is applied on plain text to produce cipher text. The Cipher text security depends on random key and on algorithm. 1.4.1 Cryptography algorithms are classified in two terms based on keys. a) Symmetric Algorithm: In Symmetric algorithm same key is used for encryption and decryption purposes like AES, HIGHT, PRESENT etc. So, in symmetric algorithm key is also shared on the network with cipher text. b) Asymmetric Algorithm: In Asymmetric algorithm different keys used for encryption and decryption purposes like RSA, ECC etc. Table 1 shows the comparative analysis of symmetric and asymmetric algorithm. 1.4.2 There are two techniques of cryptography algorithms. These are a) Block Cipher: In block cipher the plaintext bitstream break into fixed block size and same key is applied on each block for produce cipher text. Some block based cipher algorithms are AES, HIGHT, and PRESENT etc. b) Stream Cipher: In stream cipher each bit of plaintext is Exclusive- OR with key stream. The key stream is produced by some pseudorandom process. Plain Text Encryption Algorithm Key Fig.2 Block Diagram of Cryptography Cipher Text Asymmetric Algorithm of key The paper is organized as section 2 covers the literature survey. In the literature different symmetric and asymmetric algorithms and key generation are survey based on their performance and security to secure the smart grid communication. Moreover section 3 covers the comparative analysis of different algorithms for smart grids. Afterwards section 4 covers research direction on which further work can be done to secure the smart grids and finally section 5 covers the conclusion. II. LITERATURE SURVEY In the literature survey covers the symmetric and asymmetric algorithms used in smart grids for secure communication. Also, some new lightweight cryptography algorithms are survey because of their good performance. Moreover cryptography algorithms overall security depends on key randomness so some survey also done on key generation. Liu, et al., discuss how secure the two way communication between smart meter and neighborhood gateway. For securing the communication line, a lightweight authenticated scheme is proposed. In their algorithm encryption is done using Exclusive OR operation and communication line is authenticated using Lagrange interpolation formula. Their whole algorithm required very less memory and good performance so hardware efficient. Jia-Lun Tsai and Nai-Wei Lo , discuss how identitybased signature and encryption scheme used for key distribution between smart meter and service provider in smart grids without the involvement of trusted anchor. Neetesh Saxena, et al., discuss that smart grid are secure, reliable and efficient network for power distribution. There are number of users includes in smart girds like customers, different grid operators and so on. So, authentication and authorization are the big challenge in smart network. In this paper, authenticate user by their unique signature or one time password (OTP) send to their mobile phone to verify that actual user accessing the system and authorize using attribute based hash values. Uludag, et al., presents a secure data communication protocols for data collection. Smart gird is a hierarchical architecture so authentication and authorization required for communicating the data collected from measurement device to the power operator. They are using Asymmetric RSA algorithm for to create and verify signature. The parameter in their system is to optimize time. Asmaa Abdulla and Xuemin Shen , discuss how to reduce the overheads (Computation and Communication burden) of smart grids because smart grid has limited memory and area available. They proposed a lightweight secure algorithm in which cluster of houses electricity demand is forecasted in place of individual customer reports and it limits the cluster’s connection with electricity utility. Hongwei Li, et al., presents a efficient privacy preserving demand response scheme for secure the communication in smart grids. There technique have two phase in first phase the data is encrypted using homomorphic encryption to achieve privacy preserving demand aggregation and in second phase they are ensuring the session key using adaptive key evolution technique. Bassam J. Mohd, et al. , surveyed different lightweight algorithms based on their performance on software as well on hardware platform. Also, define some research issues on which in future work can be done. They are concluding that PRESENT cipher as a good reference for hardware implementation. Lang Li, et al. , proposed a QTL ultra-lightweight algorithm for resource constraint environment. QTL algorithm have based on Feistel network. The advantage of QTL algorithm is that it changes the all block messages in an iterative round as compared to conventional Feistel network where only half of block message changes. Also, to reduce the energy consumption on hardware they never doing key scheduling while maintaining security. Mohd, et al. , discuss that in low resource devices security and resource limitation are big challenge. They designed an optimized lightweight HIGHT block cipher and implement on FGPA. The algorithm is highly secure because of key scheduling and large number of rounds. Lee, et al. , proposed a lightweight LEA algorithm for resource constraint environment. LEA algorithm is 128/192/256 iterates with 24/28/32 rounds and in place of complex Substitution box they are doing simple addition, rotation and Exclusive- OR operation. LEA algorithm required only one round function so hardware efficient. Chugunkov, et al. , shows that it is possible to generate lightweight pseudorandom number generator by modifying the function of feedback. They are applying the modify function of feedback in AES for pseudorandom number and results shows that there is reasonable decrease in the classic generator parameter. Liu, et al. , discuss that overall security of cryptography algorithm depends on randomness of key. They are generating random number using tetrahedral oscillator with large jitter and for further enhancing randomness of bits the output of oscillator pass through post digital processor. They implemented the design on 0.13μm technology and bit rate after processing is 100kb/s. There design passes the NIST and Diehard test. III. COMPARATIVE In this section, different cryptography algorithms comparative analysis is done on the basis of different parameters for security are shown in table II. Table II. Comparative Analysis of Different Cryptography Algorithms Reference Symmetric/ Conventional/ Block Size Asymmetric Lightweight Number of Rounds Algorithm Asymmetric Lightweight Round:1 Liu, et al. Jia-Lun Tsai and Nai-Wei Lo  Neetesh Saxena, et al. Uludag, al. et ANAYLSIS OF DIFFERENT ALGORITHM FOR SMART GRIDS Symmetric Lightweight Round:1 Asymmetric Conventional Round:1 Asymmetric Conventional Round:1 Merits Limitation Hardware Efficient due to simple operations. For Encryption only one step Exclusive-OR so not highly secure. Unique Identity based encryption so highly secure. Highly secure because of unique signature or OTP on operator mobile number. In Hash algorithm no key is used. The time spent on encrypting a message using public key is similar to the time needed in verifying a signature. Slower than Symmetric Algorithms. Asmaa Abdulla and Xuemin Shen  Asymmetric Lightweight Round:1 Reduces the number of connection with electricity utility. Hongwei Li, et al. Asymmetric Conventional Round:1 Double Tier Security Lang Li, et al.  Symmetric Ultra lightweight Block Size: 64/128bits Rounds: 16/20 Mohd, et al.  Symmetric Lightweight Block Size:64 bit Rounds:32 Lee,  Symmetric Lightweight Block Size: 128/192/256 Rounds: 24/28/32 a) In Feistel network same architecture used for encryption and decryption purposes. b) Changes the all block messages in iterative round so highly secure. a) Feistel network based so same hardware used for encryption and decryption purposes. b) Pipeline structure gives higher throughput and less energy consumption. Key generation on the fly. Hardware Efficient et al. IV. RESEARCH ISSUES In this section, highlight the research issue determined from the literature survey. 1. In smart grids, smart meters are used to give real time customer electricity usage information. Smart meter have limited memory and area available. So, one research direction is to use lightweight algorithms in place of conventional algorithms. 2. For security purposes, block ciphers are preferred in smart meters. So, one research direction is to prefer stream Cipher in place of block cipher because limited customer information is communicated to smart grid. 3. Generate a unique signature for each smart meter so that physical clonable smart meters are not designed. 4. Authentication and Authorization are the big challenge in smart grids whenever they access intelligent electronic device, smart meters, and outdoor field equipment. So, how different user are managed in hierarchy of smart grid. So, one research direction is to provide smart card for login and also How to manage Clustering data. If there is attack on cluster data then all individual which are in the cluster are suffer from it. They break the keys into two halves and using one key for odd iterative round and one key for even rounds. So, there are chances of key attacks. Overall security depends on one function. set security in smart card that they use smart card after some biometric security like finger print scan. V. CONCLUSION In this paper, different cryptography algorithms and their related key generation algorithms are surveyed and concluded that lightweight algorithm are prefer in smart grids because limited memory and area required. Also, our research shows that symmetric algorithms are used for message encryption and asymmetric algorithms are used for authentication. Moreover, cryptography algorithms overall security depends on randomness of key so taking noise or jitter as a seed prevent from attacks. ACKNOWLEDGMENT The authors are grateful to DeitY for the financial support through ‘Visvesvaraya Fellowship’ and ‘SMDP chips to system design’ project. The authors also want to express their sincere gratitude towards the Director, Thapar University, Patiala for his persistent support and encouragement. REFERENCES         G.W. Arnold, “Challenges and opportunites in smart grids: A Position Article”, Proceeding in IEEE, Vol. 99, No. 6, pp. 922-927, Junrary 2011. 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