ABSTRACT
With the ever increasing human dependency on The Internet for performing various activities such as banking,shopping or transferring money, there equally exists a need forsafe and secure transactions. This need automatically translates to the requirement of increased network security and better andfast encryption algorithms. This paper addresses the above issue by introducing a novel methodology by utilizing the AES method of encryption and also further enhances the same with the help of visual cryptography. The complete algorithm was designed and developed using the MATLAB 2011b software. The paper also discusses a hardware approach for deploying the algorithm and elaborates on an area, speed and power efficient design on a Spartan 3E Xilinx FPGA platform AES Cryptography
The past few years have shown an inherent change between humans and the way they utilize The Internet. A few decades ago, what was used as just a source of entertainment or a hub to communicate with a few close ones though email, The Internet has now become a part and parcel of our daily lives . On an average, a daily user now utilizes the internet for booking cabs, purchasing groceries, clothes, goods, sharingprivate information in the form of videos or images and also utilizes The Internet to check his bank accounts and also to transfer money . With the advent of the Internet of Things, people can now utilize The Internet to control lights at home or even adjust the temperature of a car from any part of the world. Even though loaded with all these advantages, it must be noted that with an exchange of private and confidentialinformation such as those mentioned above, there arises a greater need to secure such data and develop fool-proof methodologies to enhance cyber security and prevent hacking . In other words, there exists a greater demand for increasing security through the field of cryptography.
The word cryptography is a culmination of two latin words – cryptos and graphy where kryptos means to hide (secret) and graphy means to write. The field involves the study of different encryption algorithms – a few of the most popular algorithms being the Advanced Encryption Standard, The DES and the triple DES . Out of all these algorithms, it has been found through research, that the AES algorithm has been the most secure and the choicest algorithm amongst all the three. The main reason for the same is the fact that the AES algorithm is immune to brute-force attack [9]. It is due to this reason, that the algorithm finds itself used in a plethora of software applications such as wireless sensor networks as can be seen in . The AES algorithm also finds itself being implemented on hardware as well – in the form of an Application Specific Integrated Circuit (ASIC) . However, it must be noted that in a hardware perspective, the area occupied by the complete architecture which performs the AES algorithm, is relatively high due to the mix column multiplier which forms a major part of the design .
The Advanced Encryption standard, as explained in the previous section, is one of the most popular algorithms due to its immunity towards brute force attack. It was first discovered by the famous Belgian scientists – John Daemen and Vincent Rijmen and is popularly known as the Rijndael algorithm, the word Rijndael obtained after the culmination of the last names of the two scientists . The AES Algorithm is capable of encrypting a 128 bit message using either a 128 bit, 192 bit or a 256 bit key. The steps involved in the AES algorithm can be seen in Fig. 1. It basically involves the Add- Round Key, followed by the sub-bytes transformation. This is in turn succeeded penultimately by the shift rows step and finally secured with the mix-column approach. The decryption process follows the same procedure but in the opposite order.
It must be noted that in all the steps mentioned above, it is the Mix column approach which is the most algorithmically intense, due to the involvement of multiplication in the Galois field (GFdomain. It is due to this reason came up with a novel methodology of pre-computing all possible multiplications in the Galois field and storing the same in theform of a look up table. This approach, also known as the LUT (Look Up Table) approach, no doubt reduces the computation time significantly, but at the same time adds on to the total on-chip area due to the storing of different values.