Symmetric algorithm

Symmetric algorithms are algorithms for cryptography that use the same key to encrypt and decrypt the message. They can be divided into [stream ciphers]? and block ciphers. The former encrypts the bits of the message one at a time, while the latter takes a number of bits and encrypts them as a a single unit. Blocks of 64 bits have been common; the Advanced Encryption Standard algorithm approved by NIST in December 2001 uses 128 bit blocks. Symmetric algorithms are generally much faster to execute electronically than asymmetric algorithms.