A simple form of encryption in which each letter in the plaintext is shifted through the alphabet a number of positions (for example A→D, B→E, C→F, etc.).

plural of substitution cipher

(cryptography) A method of encryption by which units of plaintext are substituted with ciphertext according to a regular system; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. The receiver deciphers the text by performing an inverse substitution.

(cryptography) a symmetric-key cipher in which plaintext digits are combined with a pseudorandom cipher digit stream

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.

plural of Feistel cipher

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

plural of block cipher

(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.