Encryption Algorithms: AES and RSA Encryption

April 10th, 2014 by Rossy Guide

What is AES?

The Advanced Encryption Standard (AES) is an encryption algorithm for securing sensitive but unclassified material by U.S. Government agencies and, as a likely consequence, may eventually become the de facto encryption standard for commercial transactions in the private sector. In January of 1997, a process was initiated by the National Institute of Standards and Technology (NIST), a unit of the U.S. Commerce Department, to find a more robust replacement for the Data Encryption Standard (DES) and to a lesser degree Triple DES.  The algorithm was required to be royalty-free for use worldwide and offer security of a sufficient level to protect data for the next 20 to 30 years. The specification called for a symmetric algorithm (same key for encryption and decryption) using block encryption 128 bits in size, supporting key sizes of 128, 192 and 256 bits, as a minimum.

What is RSA?

RSA (Rivest-Shamir-Adleman) is an Internet encryption and authentication system that uses an algorithm developed in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman. The RSA algorithm is the most commonly used encryption and authentication algorithm and is included as part of the Web browsers from Microsoft and Netscape. It’s also part of Lotus Notes, Intuit’s Quicken, and many other products. The encryption system is owned by RSA Security. The company licenses the algorithm technologies and also sells development kits. The technologies are part of existing or proposed Web, Internet, and computing standards. Both the public and the private keys are needed for encryption / decryption but only the owner of a private key ever needs to know it. Using the RSA system, the private key never needs to be sent across the Internet.

Comparison between AES and RSA:

Comparing the two directly is a little like comparing a tractor to a train – they’re both vehicles but have completely different function and construction. In the table below a comparative study between AES and RSA is presented in to eighteen factors, which are Key Size, Block Size, Ciphering & Deciphering key, Scalability, Algorithm, Encryption, Decryption, Power Consumption, Security, Deposit of keys, Inherent Vulnerabilities, Key used, Rounds, Stimulation Speed, Trojan Horse, Hardware & Software Implementation and Ciphering & Deciphering Algorithm.





1997 1977

Key Size

128, 192, 256 bits >1024 bits

Block Size

126 bits Minimum 512 bits

Ciphering & deciphering key

Same Different


Not Scalable Not Scalable


Symmetric Algorithm Asymmetric Algorithm


Faster Slower


Faster Slower


Excellent Secured Least Secure

Deposit of keys

Needed Needed

Key Used

Same key used for Encrypt and decrypt Different  key used for Encrypt and decrypt

Simulation Speed

Faster Faster

Hardware & Software Implementation

Faster Not Efficient

Ciphering & Deciphering


Different Different


10/12/14 1

Trojan Horse

Not proved No

Power Consumption

Low High

Inherent Vulnerabilities

Brute Forced Attack Brute Forced and Oracle attack

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