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Advance Encryption Standard (AES) is an algorithm widely used for encryption, authentication, authenticated encryption as well as in security protocols for providing security services in many modern-day applications. The primary reasons for the extensive use of AES are its stronger security and faster speed than its competitors. In the AES algorithm, different keys derived from the main key are used in encryption rounds, to provide strength to the security of the algorithm. However, in standard AES key expansion algorithm, the sub-keys are derived sequentially, that is one after other. This dependence on the previous sub-key has two problems. Firstly, the key generation cannot be parallelized, secondly, if any single sub-key is known to the attacker, all the other sub-keys, including master key, can be extracted. Also, Differential Power Analysis attack is known effective on standard AES key schedule. In this paper, we proposed a new key parallelized expansion algorithm for AES. The proposed algorithm removes the dependence on other sub-keys to provide faster speed and enhanced security. The proposed algorithm has been implemented in MATLAB software and on FPGA. The results of implementation validate that the computational efficiency of the proposed algorithm is superior to standard AES Key expansion.

The growing number of threats and attacks on communication systems has encouraged researchers to identify methods for providing security for data communication. Besides the encryption and authentication algorithms provide data security services for communication systems. However, the recent attacks on communication systems reveal that the attacks utilize the analysis of plaintext/ciphertext to breach the security of communication systems. Therefore, the plaintext should be randomized to prevent correlation between ciphertext. In this work, an algorithm is proposed for increasing ciphertext randomness in Parallel Cipher-based Message Authentication Code (PCMAC) Algorithm. The proposed algorithm utilizes the high throughput of PCMAC authenticated encryption algorithm for providing high throughput and more randomized ciphertext. The proposed algorithm is implemented for generation of Initialization Vector (IV) using the GEFFE generator and right shift operation for creating randomness in the ciphertext. The comparisons result show that the proposed implementation is more randomized as compared to the previous implementation.