With the exponential growth of internet and network applications such as e-commerce, the demand for data security increasing than ever before. Encryption algorithms play an important role in information security systems In this paper, author has proposed some modification traditional Caesar cipher. Classical Caesar cipher is mono-alphabetic and has a constant key length throughout the text file to be encrypted. Once the attacker gets the key of Caesar cipher it can be broken easily. This paper

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... roposes some modification to overcome this drawback of Caesar cipher. The proposed algorithm uses variable key for each character. Using proposed method the plain text is encrypted in such a way that it becomes difficult to decrypt. The plain text message is converted to the encrypted text using a modified Caesar cipher which uses poly-alphabetic cipher technique. The encryption is done using variable length key which depends on the string length, place of character and time of file. At the receiver end, the time will be given with name of file and if the receiver has appropriate decryption key, he can generate the text message similar to the original message. This paper is organized into three section I section is introduction which gives brief information about cryptology and its various types, attacks on cryptography etc. Section II is literature survey which includes related work in corresponding topic. Section III contain proposed algorithm. Section IV conclusion. General Terms-Information Security