共享软件中注册部分的简单实现 （2）

     来源：赛迪论坛    作者：kool

（2）将a、a²按照一定规则变换之后成为注册字符串。
实现程序如下：

// reg.cpp : Demo program for Keygen
// By Jason Li, 2001. Written for FrontFree techonology network

#include ＜string>
#include ＜iostream>

using namespace std;

typedef int BOOL;

const BOOL TRUE=（1==1）;
const BOOL FALSE=!TRUE;

// Define the magic string
const string sMagic="L5WXTUYJH7VMB4GA8SFKQN9E36RPDC";

string GetRegstr（string &sName）{
string sResult="FFTN-";
long lSum=0;
long lSum1;
long lChksum;

register unsigned int i;

// Calculate the registration string
for（i=0;i＜sName.length（）;i++）{
lSum += sName.at（i） * （i+1）;
}
// The checksum prevents accident input
lChksum=sMagic.at（lSum%30）;
sResult+=sMagic.at（lSum%30）;
lSum1=lSum;
for（i=0;i＜4;i++）{
sResult+=（char）（（lSum%10）+’0’）;
lChksum+=（（lSum%10）+’0’）;
lSum/=10;
}
sResult+=（sMagic.at（lChksum%30））;
sResult+="-";

lChksum=0;
lSum=lSum1*lSum1/3;
for（i=0;i＜5;i++）{
sResult+=sMagic.at（lSum%30）;
lChksum+=sMagic.at（lSum%30）*（（i%2）+1）; // Sum even bytes twice
lSum/=7;
}
sResult+=（sMagic.at（lChksum%36））;
sResult+="-";

lChksum=0;
lSum=lSum1*lSum1/5;
for（i=0;i＜5;i++）{
sResult+=sMagic.at（lSum%30）;
lChksum+=sMagic.at（lSum%30）*（（i%2）+1）; // Sum even bytes twice
lSum/=11;
}
sResult+=（sMagic.at（lChksum%36））;
sResult+="-";

lChksum=0;
lSum=lSum1*lSum1/7;
for（i=0;i＜5;i++）{
sResult+=sMagic.at（lSum%30）;
lChksum+=sMagic.at（lSum%30）*（（i%2）+1）; // Sum even bytes twice
lSum/=17;
}
sResult+=（sMagic.at（lChksum%30））;

return sResult;
}

int main（void）{
string sName;
string sRegstr;

// Output the prompt for user
cout ＜＜ "Registration Code Generator DEMO program version 1.00" ＜＜ endl;
cout ＜＜ "By Jason Li, 2001. For test purpose only." ＜＜ endl;
cout ＜＜ endl;

// Loop until the user name is legal to the algorithm
do{
// Get the user name
cout ＜＜ "Enter the user’s name （5 chars min）, followed by comma（,）: ";
getline（cin, sName, ’,’）;
}while（sName.length（）＜=5）;

cout＜＜"User "＜＜sName;

sRegstr=GetRegstr（sName）;

cout＜＜" has the registration string of "＜＜sRegstr;
cout＜＜endl;

return 0;
}

程序按ANSI C++标准编写，在Visual C++ 6和GNU C++中运行通过。