AES (Advanced Encryption Standard) is a symmetric cipher, which is currently used for protection of the most sensitive information. The underlying algorithm, Rijndael, has been created in 1998, when a public competition for a new encryption standard (to replace DES standard) has been launched. Its authors are two Belgian cryptographers (Rijmen and Daemen, that is why "RijnDael"). The Rijndael algorithm won the competition and was re-labeled as AES (for details, see Wikipedia).
This symmetric cipher has soon gained a reputation of a very fast, but also very secure algorithm. Despite 7 years of scientific work, no real security problems with AES have been discovered. That is why AES is currently used for protection of very sensitive data both in civilian and military environment. For example, communication of American diplomacy and military is protected using AES.
The AES standard uses keys of variable length - 128, 192 and 256 bits. The longer key lengths – 192 and 256 bits – have been approved by NSA (National Security Agency, an American bureau for protection of secrets) to protect even the „top secret“ data.
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