Cryptography is an ancient technique of data security that is used to protect data from unauthorized access. It is used in many applications on commercial organizational or industrial scales to secure data. Data encryption is a process of converting data into cipher text. This is the most effective way to achieve data security. In this paper, we have imposed a new method to enhance the vigenere cipher for more efficiency and security. Though, the classical Vigenere cipher is extremely easier to crack and also vulnerable to attacks. To improve the data confidentiality of cipher text security features, we use the Relative Frequency of Alphabetic Letters. We arranged the sequence of the letter according to the relative frequency and arranged them in increasing order and then we performed some modifications in the Vigenere cipher by using the relative letter frequency technique and then compressed the text data. The proposed procedure improves the confidentiality of a text message by introducing multiple layers of security processes such as encryption and decryption, and compression, respectively. The purpose of this article is to improve the security of classical Vigenere cipher based on using relative frequency analysis for the encryption to secure the data and then the lossless Huffman technique compresses the resultant generated text. To sum up, the ensuing proposed technique produces a more secure and short length of data code than the existing process.

Keywords : vigenere cipher; Huffman; relative letter frequency; and data compression.