Enhancing The Security of Caesar Cipher Using Double Substitution Method

Cryptography comes from the Greek words for "secret writing". The plain text is encrypted into the corresponding cipher text, using an algorithm and a key. Substitution and Transposition are two techniques used for converting data into non-readable form. Caesar Cipher is an example of substitution technique. In this paper we have proposed a cipher that uses basic encryption techniques of substitution and transposition. A single columnar transposition followed by a double substitution is applied on a Caesar cipher in order to make it a stronger and a more secure cipher.