1. The United States encryption standard that replaces the older/weaker DES standard. Contrast: The main impetus behind AES to replace DES is the support for larger key sizes. DES uses 56-bit keys, which can be cracked in just a few minutes (in the year 2001). In contrast, AES supports 128-bit keys (as well as 192-bit and 256-bit). Whereas both DES and AES are fundamentally block-ciphers, AES is also designed to be an efficient stream-cipher and hash algorithm. Whereas DES was designed to be hardware based (software implementations are much slower), AES has been designed to be efficient in both software and hardware. In particular, implementations in ANSI C, Java, and x86 assembly language were important. Another important criteria was the ability for the algorithm to work within smart-cards with slow CPUs and limited memory. Key point: The NIST director in charge of selecting the AES algorithm says: "If Moore's law continues and quantum computing doesn't manifest itself, then I think this system will have a good 30 year run". Misconception: AES does not replace DES. In the 1980s, DES was the most used encryption algorithm. However, due to length of time it took the government to come up with a replacement standard, other encryption algorithms became widely used, such as RC2, RC4, Blowfish, IDEA, and Triple DES. Moreover, crypto has became very "pluggable", with many products supporting numerous simultaneous encryption algorithms. From Hacking-Lexicon