多数程序设计语言处理整数的能力时有限的，如C语言中，int类型数据范围是-32768－32767。实际问题的处理过程中往往涉及大整数的运算，如RSA加密算法要求至少64bit的整数，设计算法实现大整数的加减运算。-majority programming language processing integral to the limited capacity, such as C language, int data type is the scope -32768-32767. Practic

多数程序设计语言处理整数的能力是有限的，如C语言中，int类型数据范围是-32767----32767。实际问题的处理过程中往往涉及大整数的运算，如RSA加密算法要求至少64bit的整数，本程序是设计算法实现大整数的加减运算。-majority programming language processing is integral to the limited capacity, such as C language, int data type is the scope -32767 ----

IMPLEMATATION DES CRIPHER IN C++ The Data Encryption Standard (DES) is a block cipher that uses shared secret encryption. It was selected by the National Bureau of Standards as an official Federal Information Processing Standard (FIPS) for the Unit