Symmetric-key algorithm

Symmetric algorithms are algorithms for cryptography that use the same key to encrypt and decrypt the message (see Cryptography/Keys). They can be divided into stream Ciphers and block Ciphers. The former encrypts the bits of the plaintext one at a time, while the former takes a number of bits and encrypts them as a a single unit. Normally blocks of 64 bits are used. Symmetric algorithms are faster to execute electronically than Asymmetric algorithms.