n cryptography , a cipher (or cypher ) is an algorithm for performing encryption or decryption —a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment . To encipher or encode is to convert information from plain text into cipher or code. In non-technical usage, a 'cipher' is the same thing as a ' code '; however, the concepts are distinct in cryptography. In classical cryptography , ciphers were distinguished from codes