Advanced Encryption Standard (AES) Implementation in Embedded

Advanced Encryption Standard (AES) Implementation in Embedded Systems Book Chapter "Embedded Systems". Editor Kris Iniewski, Wiley 2012

The word cryptography refers to the change of data representation from its original form into another different form to make it hidden and secured. Cryptography has two processes; the first process is the encryption where the original data is converted into secured form using certain steps. The second process is the decryption, where the encrypted data is restored to the original form by applying the inverse to the steps applied in the encryption process. Classical cryptography started thousands of years ago. Historically, classical cryptography was used for secret communications between people. This kind of cryptography is usually applied by substituting the message letters by other letters using certain formula, for example substituting each letter in a message with the next letter in the alphabets so that the word “Test” would become “Uftu”. In modern ages, cryptography development has been a major concern in the fields of mathematics, computer science and engineering. One of the main classes in cryptography today is the symmetric-key cryptography, where a shared key of a certain size will be used for the encryption and decryption processes. Nowadays cryptography has a main role in embedded systems design. As the number of devices and applications which send and receive data are increasing rapidly, the data transfer rates are becoming higher. In many applications, this data requires a secured connection which is usually achieved by cryptography. Many cryptographic algorithms were proposed, such as the Data Encryption Standard (DES), the Elliptic Curve Cryptography (ECC), the Advanced Encryption Standard (AES) and other algorithms. Many researchers and hackers are always trying to break these algorithms using brute force and side channel attacks. The DES algorithm starts to fail after several published brute force attacks. The linear cryptanalysis attack could break the DES and made it insecure algorithm. The NIST started to search for another algorithm to replace the DES, where the Rijndael cipher was selected as the new Advanced Encryption Standard (AES).

The Advanced Encryption Standard (AES) is considered nowadays as one of the most secured published cryptographic algorithms, where it was adopted by the National Institute for Standards and Technology (NIST) after the failing of the Data Encryption Standard (DES). Moreover, it is used in many applications such as in RFID cards, ATM Machines, cell-phones and large servers. Due to the importance of the AES algorithm and the numerous applications that it has, the main concern of this chapter will be presenting new efficient hardware implementations for this algorithm.