International Journal of Security and Its Applications Vol. 9, No. 5 (2015), pp. 55-60 http://dx.doi.org/10.14257/ijsia.2015.9.5.05 ISSN: 1738-9984 IJSIA Copyright ⓒ 2015 SERSC The RC7 Encryption Algorithm Rashmi 1 , Vicky Chawla 2 , Rajni Sehgal 3 and Renuka Nagpal 4 1,2 Student, Dept. of Computer Science & Engineering, Amity University, Uttar Pradesh 3,4 Assistant Professor, Dept. of Computer Science & Engineering, Amity University, Uttar Pradesh 1 rashmikr1993@gmail.com, 2 chawlavicky497@gmail.com 3 rsehgal@amity.edu, 4 rnagpal1@amity.edu Abstract Cryptography can be defined as the art of secret writing or protecting information by transforming it (encrypting it) into an unreadable format, called cipher text and then transmitting it across insecure networks, so that it cannot be read by anyone except the intended recipient. Only those who possess a secret key can decipher (or decrypt) the message into plain text. Encrypted information can sometimes be broken by cryptanalysis, also called code breaking, although modern cryptography techniques are virtually unbreakable. Various algorithms help achieve flawless encryption results which are mostly unbreakable. This paper is an attempt to improve one such algorithm, i.e. RC6 by adding on to its existing functionalities. Keywords: Cipher text, Cryptanalysis, Cryptography, Decryption, Encryption, RC6 1. Introduction As e-mail, chat and other forms of electronic communication become increasingly necessary by the day, it becomes all the more important to simultaneously protect and maintain the security of all the data involved in these operations. To achieve this, cryptography comes into the picture. Cryptography is achieved by using various algorithms which are based on either substitution of plain text with some cipher text, or by using certain transcription techniques, or a combination of both. Based on the type of key being used, the algorithms could be classified into Symmetric key algorithms (e.g., AES, DES, RC5, Blowfish, etc.,) and Asymmetric key algorithms (e.g., RSA, MD5, SHA, etc.,). Symmetric key algorithms are those in which encryption and decryption are performed using the same key. Asymmetric key algorithms are the ones in which encryption and decryption are performed using different keys. The RC algorithms are a set of symmetric-key encryption algorithms invented by Ron Rivest. The "RC" may stand for either Rivest's Cipher or, more informally, Ron's code. There have been six RC algorithms so far. We have proposed an improvised version of the RC-6 algorithm, namely RC-7 in our paper. 2. Related Work RC4 is a stream cipher designed in 1987 by Ron Rivest for RSA data Security (now RSA Security) [1, 2]. It is a variable key-size stream cipher with byte-oriented operations. This algorithm is used for random permutation. RC4 is used in the Secure Sockets Layer/Transport Layer Security (SSL/TLS) standards that have been defined for communication between Web browsers and servers [3].