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An Efficient Implementation of AES algorithm using Custom Key

Cryptography in the digital era plays an irreplaceable role in data security by providing integrity, authentication, and confidentiality to protect sensitive data from unauthorized access. Though Advanced Encryption Standard (AES) is an approved symmetric cryptographic algorithm, it needs improvement in terms of speed, area, and security. In the proposed work, unified AES 128-bit and 256-bit cipher text are implemented with iterative encryptor and decryptor core, to optimize area and delay. For this, compact and combined MixColumn / Inverse - MixColumn operations are introduced in the algorithm. Also, “The Transported Subbyte Operation” has been modified, where each byte in the matrix is swapped before S box substitution to enhance the security level. Simulation of the proposed work is carried out using ModelSim-Altera 6.3g_p1 (Quartus II 8.1). The enhanced modified algorithm resulted in an area reduction of 21.27% and a delay reduction of 16.99%.