Enhanced Key Expansion Algorithm for Advanced Encryption Standard using Different S- Box Implementat

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GRD Journals- Global Research and Development Journal for Engineering | Volume 1 | Issue 5 | April 2016 ISSN: 2455-5703

Enhanced Key Expansion Algorithm for Advanced Encryption Standard using Different S- Box Implementation on FPGA Amrutha T V PG Scholar Department of Electronics & Communication Engineering KIT, Tiptur, India

N R Prashanth Associate Professor Department of Electronics & Communication Engineering KIT, Tiptur, India

Abstract The main aim of this paper is encrypt the data using Advanced Encryption Standard (AES) algorithm. In AES algorithm cryptography technique is used. Security is most important in data communication so to increase the security key expansion algorithm is used. In this paper we considering different sizes of S-box to reduce the area and the LUTs. To reduce LUTs here considering the affine transformation method is used. The round key expansion is proposed to improve security against attacks. Encrypted data is decrypted using inverse AES algorithm method. In AES algorithm numbers of round performed during execution will be depended upon the Key length. Here AES -128-bit key are used, so number of round performed during execution will be 10. This algorithm is simulated using Xilinx software and implemented on FPGA. Keywords- Advanced Encryption Standard; FPGA; Key expansion; Sub word; Rotword; Rconst

I. INTRODUCTION Cryptography assumes a vital part in securing the data, which empowers to store delicate data or transmit it crosswise over unreliable systems so that unknown persons can't get it. The Advanced Encryption Standard (AES) was distributed by the National Institute of Standards and Technology (NIST) in 2001. AES is a cryptographic calculation that is utilized to secure electronic information and it has symmetric block cipher with a piece length of 128 bits that can encipher (scramble) the information. The AES calculation comprises of three fundamental parts: 1) cipher (Encryption), 2) inverse Cipher (Decryption) 3) Key Expansion. Encryption changes over information to a mixed up structure called as cipher content. decryption changes over the cipher content once again into its indigenous structure that is original information. The AES calculation is equipped for utilizing diverse cryptographic key lengths of 128, 192, and 256 bits to encipher and decipher the information. Key development is utilized for creating the keys for 10 adjusts that are delivered from the first data key. Each round key are not the same as each other to enhance the security of the calculation. In this manner it inessential to enhance the Performance of the key development from the exteral attacks. But the tradition key extension of AES has some security issue because of the key courses of action are relying on the past key rounds. Thus, once again calculation of key development is proposed to enhance the security of the Advanced Encryption Standard for 128-piece key size.

II. ADVANCED ENCRYPTION STANDARD ALGORITHM A. AES Specification The length of the info hinders, the yield square and the State is 128 bits for the AES calculation which is spoken to by Nb = 4. The information 128-bits are organized in 4 × 4 grid into16 bytes that mirrors the quantity of 32-bit words (number of segments) in the State. The AES calculation will bolster in any event of the three key lengths: 128, 192, or 256-bits (i.e., Nk = 4,6, or 8, individually). The length of key is spoken to by Nk =4, 6, or 8 which mirrors the quantity of 32bit words (number of segments) in the Cipher Key. The quantity of rounds for ASE calculation tbe performed amid the execution is reliant on the key size. The quantity of rounds is spoken to by Nr, where N10 when Nk = 4, Nr = 12 when Nk = 6, and Nr = 14when Nk = 8. AES calculation utilizes a round capacity for both its Cipher and Inverse Cipher that is made out of four distinctive byte arranged changes:  Byte substitution utilizing a S-box lookup table.  Row-wise stage of the State cluster by various balances  Column-wise blending inside every section of the State exhibit  Addition of round key to the State.

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