Modified Hill Cipher Using Vandermonde Matrix and Finite Field

Cryptography is the science which provides confidentiality, authenticity and integrity to the users over the prevailing insecure communication channels. Encryption is the transformation of data into some unreadable form. The purpose is to ensure privacy by keeping the information hidden from anyone for whom it is not intended, even those who can see the encrypted data. Decryption is the reverse of encryption; it is the transformation of encrypted data back into some intelligible form. Encryption and decryption require the use of some secret information, usually referred to as a key. Hill cipher in cryptography is a symmetric key substitution algorithm, which is vulnerable to known plain text attack. We modify the existing Hill cipher by using Vandermonde matrix and introducing the elements of finite field which provides more security to the said cipher.