James P. Johnson

The coding per block (in English block cipher ) is one of the two main categories of modern codings in symmetrical Cryptographie, the other being the Chiffrement by flood. The principal difference comes from cutting of the data in blocks of generally fixed size (often a power of two ranging between 32 and 512 bits). The blocks are then quantified the ones after the others. It is possible to transform a coding of block into a coding by flood by using a Mode of operation like ECB (each block quantified independently of the others) or CFB (one chains coding by carrying out a XOR between the successive results).

An not-exhaustive list of codings per block:

OF the, the ancestor designed in the Seventies, was passably studied
AES, the substitute of
Blowfish and Twofish, alternatives to AES

There are of them still well others which are adapted to particular needs. Some consume more memory or are greedier in computing power. A coding per block can also be used like a Fonction of chopping, i.e. a function with one way. An alternative of is employed for the system of passwords in Unix. A chain containing only of the zeros is quantified with a key corresponding to the password (a random component called " sel" is still integrated into the algorithm). This coding is iterative and is made 25 times before obtaining the end result.

See too

Cryptanalyse

External bond

self-educated Course of coding per block of Bruce Schneier

and its French-speaking version: Individual course of cryptanalyse

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