# Electronic Code Book - Computer Definition

An operation mode in cryptography for a block cipher such that each possible block of plaintext has a particular ciphertext value, as well as the reverse. Put another way, the same plaintext value will always result in the same ciphertext value. Electronic Code Book is used when a bulk of plaintext is broken down into several blocks of data. Each block is then encrypted independently of the other blocks so that it has the capability to support a different encryption key for each block type.

See Also: Cryptography or “Crypto.”

TechTarget. Electronic Code Book. [Online, July 26, 2001.] http:// searchsmallbizit.techtarget.com/gDefinition/0,294236,sid44_gci344944,00.html.

In cryptography, the simplest mode of operation used with a block cipher to provide the complete encryption algorithm. Each block of regular text (plaintext) is encrypted with the cipher as a unit and turned into encrypted text (ciphertext). The weakness in the electronic code book (ECB) method is that repeating plaintext generates repeating ciphertext from which cryptanalysis can more easily derive the secret keys. When the letters ECB follow a cipher, it denotes the electronic code book mode is used; for example, DES-ECB and AES-ECB. See mode of operation, block cipher and cryptography.