A-RSA: Augmented RSA

Today, RSA algorithm is the most widely used public-key cryptosystem around the world. It is used for security in everything from online shopping to cell phones. However, the basic RSA is not semantically secure, i.e., encrypting the same message more than once always gives the same ciphertext. For this reason, the basic RSA is vulnerable to set of indirect attacks, such as known plaintext, chosen plaintext, timing, common modulus, and frequency of blocks (FOB) attacks. Moreover, RSA is known to be much slower than the standards symmetric key encryption and it does not used for encrypting large data. In this paper, we design and implement a swift and secure variant of RSA based on Rabin and Huffman coding called Augmented RSA (A-RSA) to solve aforementioned limitations of the basic RSA. A new additional randomization component r is added in A-RSA. This component is encrypted by Rabin algorithm to improve the security level of RSA against the indirect attacks and make RSA semantically secure. Moreover, A-RSA makes the factorization problem harder, since the attackers need to break the factorization of large numbers for both RSA and Rabin. Besides, employing Huffman Coding compression in A-RSA prevents FOB attack and speeds up the execution time for the A-RSA. Our testing results over set of file sizes of 1MB, 2MB, 3MB, to 10 MB show that A-RSA's average execution time is equal to 0.55 of the average execution time of the basic RSA in encryption process and 0.01 in decryption process. Also, we found that RSA system increases the size of ciphertext by 1% compared to the original file size, while the average size of A-RSA files is equal 0.46 of its original sizes.