Low cost AES crypto core

AES (Advanced Encryption Standard) is state of the art symmetric cipher. This study illustrates a new approach to low cost and efficient implementation of AES cipher on 8 bit microprocessors. This crypto processor implementation is recommended for low speed applications where cost, availability and ease of developing and manufacturing come in. Most efficient possible implementation of Galois field multiplication and key expansion on 8 bit microprocessors is demonstrated. Decryption algorithm is modified for two way communication without any overhead. Two modes of operations are considered, Electronic Codebook and Counter mode. Counter mode is further optimized for lowest latency due to its pre-processing feature.