The Advanced Encryption Standard (AES) is a mathematical algorithm or cipher used to conceal information so that it cannot be read by unauthorized computer users when it is stored or in transit. The science of writing in secret code is called cryptography, and AES can be more accurately described as a cryptographic algorithm. Furthermore, the process of scrambling or encrypting data provides other benefits besides ensuring that information remains confidential.
Encrypting a message can also prove that a message is authentic and enforce non-repudiation, which is a process that prevents an individual from denying that he sent a message or was involved in a transaction. This is because cryptography can be used to create a code that is not only unintelligible but also unique. The unique code acts like a fingerprint and cannot be changed without a private decryption key, so it is bound to specific message, transaction, or individual.
The Advanced Encryption Standard was selected in October of 2000 by the National Institute of Standards and Technology (NIST), primarily as a replacement for the Data Encryption Standard (DES). While DES had been widely used since the 1970s as the official US government encryption standard, it has currently been broken many times and can no longer be trusted for security.
Officially, the selection process began in January 1997 when the NIST initiated a request for proposals based upon a list of requirements for a new more secure cryptographic algorithm. NIST wanted the new algorithm to be flexible enough to work on physical devices as well as computer programs. It also had to be robust enough to work on older machines and function for decades into the future.
The NIST, in collaboration with government, education, and industry groups, initially chose 15 candidates for early examination. Five finalists were chosen for more extensive testing. The eventual winner was a cipher called Rijndael that was designed by two Belgian cryptographers, Vincent Rijmen and Joan Daemen, whose surnames form the basis for the algorithm’s name. Rijndael, more commonly called Advanced Encryption Standard, is the official cryptosystem used for encrypting US government applications.
Advanced Encryption Standard is a symmetric algorithm, which means that it uses a single key to encrypt and decrypt messages. A person should keep in mind that a key is simply a variable inserted into the algorithm to randomize the data. Since AES relies on a single key to do both tasks, it is imperative that the key remain secret. If an unauthorized user was able to obtain the key, he would be able read all encrypted messages.