Due to increasing use of computers, security of digital information is most important issue. An Intruder is an unwanted person who reads and changes the information while transmission occurs. This activity of intruder is called intrusion attack. To avoid such attack data may be encrypted to some formats that is unreadable by an unauthorized person. Advanced Encrption System is mainly an advance version of Data Encryption Standard. Efforts towards developing Advanced Encrption System was started by National Institute from January 1997.Using Cryptography is essential so that the medium of file communication can secured, as its main objective is implementing the public and private key(s) with hash functions or authentication codes or digital signatures. However it provides confidentiality by itself because mostly, the concerning person knows that the message is hidden in what kind of medium (Ali et al., 2011).
1.1 Background of the StudyThe most powerful and common approach to countering the threats to network / information security is using Encryption (Ayoub, 1994). Encryption is based on number of substitutions, transpositions we perform on the plaintext, converted plain text is treated as cipher text and a process of converting is called Cryptography (William, 2005). Even though encryption is very powerful among these two, the cryptanalysts are very intelligent and they were working day and night to break the ciphers. To make a stronger cipher it is recommended that to use: More stronger and complicated encryption algorithms with more number of rounds, Keys with more number of bits (Longer keys), secure transmission of keys (Ravindra, 2010).