Code (cryptography)

In the context of cryptography, a code is a method used to transform a message into an obscured form, preventing those not in on the secret from understanding what is actually transmitted. The usual method is to use a codebook with a list of common phrases or words matched with a codeword. Messages in code are sometimes termed codetext.

Related Topics:
Cryptography - Message - Codebook

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Terms like code and in code are often used to refer to any form of encryption. However, there is a major distinction between codes and ciphers in technical work; it is the scope of the transformation involved. Codes work at the level of meaning; that is, words or phrases are converted into something else. Ciphers work at the level of individual letters, or small groups of letters, or even, in modern ciphers, with individual bits. While a code might transform "attack" into "FRGPL" or "mincemeat pie", a cipher transforms elements below the semantic level, ie, below the level of meaning. The "a" in attack might be converted to "Q", the first "t" to "f", the second "t" to "3", and so on. Ciphers are more convenient than codes in some situations, there being no need for a codebook.

Related Topics:
Encryption - Cipher

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Codes on the other hand, were long believed to be more secure than ciphers, there being (if the compiler of the codebook did a good job) no pattern of transformation which can be discovered. With the advent of automatic processors (ie, in recent times the electronic computer), ciphers have come to dominate cryptography.

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