Application of Extended Euclid Algorithm on Hill Cipher Cryptography Modulo 95

Abstract

Hill Cipher Cryptography is the art of hiding a message using an invertible matrix as the key. Let A be a 2 2 invertible matrix of the real number. Encryption performed by converting each character on the original message into an ASCII code. The result of the conversion is multiplied by matrix A using matrix multiplication operation modulo 95 which result added with 32. The calculation result in the form of numbers is re-converted into characters according to the ASCII code. It is described in parallel, while the ciphertext matrix is operated using matrix A^(-1). Since matrix A is an invertible matrix and not supposed to have 1/-1 determinant, the matrix result is possibly a non-integer real number. Therefore, the extended Euclid algorithm is needed to finish the description process for finding out the modulo 95 number of a non-integer real number.

Keywords

• cryptography
• Extended Euclid
• modulo 95
• hill cipher