资料介绍
In January 1977, The United States government
adopted a product cipher developed by IBM as its offi-
cial encryption standard [1]. This algorithm, called the
Data Encryption Standard (DES), has been adopted as
a worldwide standard for data encryption by ISO (Inter-
national Standards Organization) [2, 3]. This applica-
tion note describes the implementation of the DES
algorithm on PIC17C42. AN583
Implementation of the Data Encryption Standard Using PIC17C42
Authors: Al Lovrich
KEY SCHEDULE
Mark Palmer The DES uses a 64-bit key for encryption and decryp-
Microchip Technology Inc. tion process. Initially, the original 64-bit key is reduced
to 56-bit by ignoring every eighth bit. In general these
INTRODUCTION bits are used as parity bits to make sure that there were