AES, or the Advanced Encryption Standard, also known as part of the Rijndael cipher method because it was taken partly from it, was invented in 2001. This is a symmetric three-block cipher. Each of these cipher blocks has a key size of 128-bits and has corresponding key ciphers of which are from 128-bit to 256-bit in size. This is one of the most popular ciphers ever in use, and most that need this type of encryption are using it, such as the government and the military, as well as many major vendors and security firms around the world.

This cipher, which was announced in 2001, underwent a standardization and evaluation process. In the five years this evaluation process lasted, AES competed against 15 other encryption methods. This one was finally chosen as the standardized, trusted and unbreakable encryption technique, winning against the odds to eventually become the first AES method available to the public. It is also an open source cipher from which others can use the original code and information of AES to create new ciphers.

This technique is one of the fastest and can be used in both software and hardware implementation. It uses a network consisting of substitution permutation and does not use the Feistel method to work, unlike its competition. Using multiple processes, including Key expansion, an initial round, four subrounds and a final round, the cipher encrypts the information using a four by four byte array, which is called a “state” and the calculations are completed in the finite field. The amount of rounds used depends on what size the keys are. For example, a key with 128-bits uses 10 rounds and a key with 256-bits uses nine rounds.

Attacks against this method of encryption are almost unheard of. To date, there have been various low level attacks, however these were forced onto the lower round encryption than is normally used. The attacks were never completed because the attackers could not decrypt the information before they were caught. This method is what most government and military agencies use for data protection today.

The initial release of the AES encryption technique came on the heels of the DES technique’s failure. This one has a much smaller bit cycle, only a key of 56-bits and the key and encoding were easily deciphered. Since the switch to the new standard, AES, the government has kept its information much safer.

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