What Is AES Encryption?

Advanced Encryption Standard (AES) is a symmetric key cipher technique used to secure and encrypt operating systems, hard drives, networking systems, files, e-mails, and other similar electronic data. It typically consists of three block ciphers taken from a larger collection published originally as Rijndael, a name created from the surnames of the two Belgian cryptographers who first devised the cipher and initiated its use. The standard was commissioned by the U.S. government as a way of protecting classified information, though today it’s used by a number of governments and electronic security firms around the world. Each cipher has a 128-bit block size with three different key sizes of 128, 192, and 256 bits. Though not entirely impenetrable, it’s widely considered one of the strongest ciphers available.

The digital space makes it very easy to share and store a range of data and documentation, but this ease of access can work both ways: without proper protections, information can and often is compromised, whether accidentally or as a deliberate action. Encryption techniques aim to scramble the data packets transmitted from one point to another, and also act as a barrier or vault surrounding information stored on fixed servers or hard drives. The AES standard is one of the strongest and most complex cryptographic tools.

Understanding the mechanics of the AES cipher usually requires at least some knowledge of encryption, which can be complex. Put simply, though, the cipher works by executing a number of transformation rounds repetitiously; this converts the input plain text into an output of cipher text. There are several processing steps for each round with one round that relies exclusively on the encryption key. Then, a set of reverse rounds are applied to convert the cipher text back into plain text. Encryption with AES only uses one 128-bit key to encrypt and decrypt data.

The United States National Institute of Standards and Technology (NIST) was the standard’s original pioneer. It made a request for encryption algorithms for the AES standard in 2000, and accepted proposals from cryptographers worldwide. Two Belgian computer scientists, Joan Daemen and Vincent Rijmen, worked together to create what they called the “Rijndael cipher,” which they submitted to the selection process and were ultimately chosen.

The US government began implementing the standard into its systems to help secure classified and non-classified information in early 2001. By November of that year, AES was chosen by NIST as the Federal Information Processing Standard (FIPS), also known as FIPS197. In July 2003, the National Security Agency (NSA) stated that AES was secure enough to protect its information at the secret and top-secret levels.

AES encryption is used around the world to secure some of the most protected systems for both governmental groups and business. It is even used by individuals to protect private computers and networking systems, and is generally the standard set by the US government and most corporations and agencies worldwide.

One of the reasons why this sort of encryption works so well is that it works on multiple network layers at the same time. Although AES and Rijndael are used interchangeably, there are some differences that should be noted. While AES uses a fixed 128-bit block cipher and three key sizes of 128, 192 and 256 bits, Rijndael can be used with any size block cipher and key in multiples of 32-bits. Rijndael ranges from 128-bit to 256 bits for its key and block cipher sizes.

While AES encryption is not unbreakable, it is generally considered highly secure. Until 2009, it was believed that only a side-channel attack could get through an AES-protected system. In 2009, related key attacks and known-key distinguishing attacks were reported. Some of the attacks on AES systems are difficult to complete; for example, attacks typically require a user to be on the same system as the AES encryption software to break the cipher.