dgEncrypt is an implementation of the Rijndael block cipher, which has recently been selected by the National Institute of Standards and Technology (NIST) as the new Advanced Encryption Standard (AES) for the U.S. government. The Rijndael cipher is a symmetric key block cipher, which is a type of cipher that encrypts data in blocks, rather than a single bit at a time, and uses the same key for both encryption and decryption. For its enciphering functions, dgEncrypt employs a version of Rijndael that operates on 128-bit input blocks, with keys that are 128, 192, or 256 bits in length. A second version of the Rijndael cipher, which operates on 256-bit input blocks with 256-bit internally generated keys, is used to generate cryptographically viable random values, such as cipher keys.