Definition:Cipher (Cryptography)

Definition

A cipher, in the context of cryptography, is an algorithm used to transform a message into another string of symbols in order to hide its meaning from a third party.

A cipher operates by replacing each symbol in the original string with a word in some alphabet.

The specific nature of the replacement depends on the specifics of the cipher.

In the context of cryptography, the plaintext is the message being transformed into an encrypted string.

In the context of cryptography, the ciphertext is the ciphered string after the plaintext has been processed by the cipher.

In the context of cryptography, the key is the rule which allows the ciphertext to be transformed back into the original plaintext.

Results about ciphers in the context of cryptography can be found here.

The word cipher can also be found in its less common spelling: cypher.

The word ultimately derives from the Arabic صِفْر‎ (ṣifr), meaning zero or empty.