Implementation of the Data Encryption Arithmetic of DES Basing on C Language

摘要

The system of DES being issued by ISO is a data encryption standard. After analyzing the arithmetic of DES, this article brings forward realizing DES using C language. Passing circulation or iteration this article uses ordinary base arithmetic (for example, shift left, shift right, addition of mode 2, etc an) and commutation (choice function, replace function) constructing the nonlinear transform of data stream (encipher commutation or decrypt commutation) to realize cryptogrammic protect for the data of computer. This article emphasize to introduce primary encipher course which is realized by C language.