AES: Current security and efficiency analysis of its alternatives

The Advanced Encryption Standard (AES) has been in existence over the last 11 years. It was widely accepted as the de facto standard in many security-related applications such as SSL/TLS, Microsoft BitLocker Drive Encryption, Skype and many others. Recently in 2011, the AES was claimed to be theoretically broken in the single-key attack model using a new technique called biclique. Just two years before in 2009, the AES with 192- and 256- bit keys were found to be theoretically broken in the related-key attack model. This paper reviews existing attacks on the AES and evaluates the efficiency of recent block cipher proposals as alternatives to the AES. These block ciphers were proposed to patch the AES against the related-key type of attack.