Advanced Encryption Standard (AES)

AES was developed in response to the cybersecurity needs of the US government. In 1977, federal agencies relied on the Data Encryption Standard (DES) as their encryption algorithm. DES was created by IBM with a 56-bit symmetric key cipher design and has been used successfully for almost 20 years. By the 1990s, it was clear that DES was no longer a secure standard for the agencies. According to Moore’s law, greater computing power meant that a 56-bit system was inadequate against brute force attacks. A more sophisticated encryption standard was urgently needed.

In response to such need, the government announced a public competition to find a replacement system. Over the following five years, 15 proposals were narrowed down to five finalists before a final winner was ultimately selected. By making the competition public, the government could be sure that no system had a backdoor and the chances of identifying and fixing flaws were maximized.

Ultimately, Rijndael’s cipher emerged as victorious. This was a symmetric-key block cipher similar to DES but much more sophisticated, Rijndael was developed by—and named after—two Belgian cryptographers, Vincent Rijmen and Joan Daemen. In 2002, it was renamed the Advanced Encryption Standard and published by the National Institute of Standards and Technology.

With AES, the same secret key is used for both encryption and decryption, and both the sender and recipient of the data need a copy of the key. In contrast, asymmetric key systems use a different key for each of the two processes. Asymmetric keys are best for external file transfers, while symmetric keys are better suited for internal encryption. The advantage of symmetric systems like AES is their speed. Because a symmetric key algorithm requires less computational power than an asymmetric one, it is faster and more efficient to execute.