A manual symmetric encryption technique that encrypts pairs of letters (digraphs).

A text encryption technique that uses a series of different Caesar ciphers based on the letters of a keyword.

(cryptography) A symmetric structure used in the construction of block ciphers. It is an iterated cipher with an internal function called a round function.

(cryptography) Any deterministic cipher that operates on fixed-size groups of bits (binary digits), called blocks, with an unvarying transformation specified by a symmetric key.