Hill Cipher is a first polygraphic substitution cipher that works on digraphs, trigraphs (3 letter squares) or hypothetically blocks of any magnitude. The Hill Cipher utilizes a region of science called Linear Algebra, and specifically requires the client to have a rudimentary knowledge of matrices. It additionally makes utilization of Modulo Arithmetic (like the Affine Cipher). To perform decryption, the hill cipher requires the inverse of the key matrix. This is the major shortcoming of Hill cipher since every key matrix is not invertible. We will propose a new variant of hill cipher, which will find the decryption of the cipher text even when the key matrix is non invertible.

Hill Cipher Invertible key matrix offset determinant.