In cryptography, a codebook is a document used for implementing a code. A codebook contains a lookup table for coding and decoding; each word or phrase has one or more strings which replace it. To decipher messages written in code, corresponding copies of the codebook must be available at either end. The distribution and physical security of codebooks presents a special difficulty in the use of codes, compared to the secret information used in ciphers, the key, which is typically much shorter.

NSA documents sometimes use "codebook" to mean 'block cipher'; compare their use of "combiner-type algorithm" to mean 'stream cipher'.

In social sciences, a codebook is a document containing list of codes used in research.

A codebook is usually made in two parts, one part being the plaintext to ciphertext, the second being the other way around.

The first part is often based like a dictionary, in some way or another. The second part is also usually like a dictionary, but with the code words being like a dictionary.

An example of an algorithm using a codebook is the MacGuffin cipher.

BCUZ.com FACTS Encyclopedia content is licensed under the GFDL as approved by Wikipedia.
For more information review our copyright contact and privacy policy. © 1996 - BCUZ.COM - We have all the FACTS you need about Small Business Financing, Behavior Disorder, Having Too Many Bills, Needing Cash Fast, Structured Settlements, Frequent Flier Programs, Top Steak Houses, The Mayan Indians, Norfolk and Suffolk England, Growing Longer Hair and a full reference English Encyclopedia and Spanish Encyclopedia.Privacy Policy