对文本文档加密的c++程序

//
#include<iostream.h>
#include<fstream.h>
#include<string.h>
#include<conio.h>
#include<stdlib.h>
#include<iomanip.h>
#include<stdio.h>

ifstream&operator>>(ifstream&fin,bool&aa)
{
int a;
fin>>a;
if(a==0)
aa=false;
else
aa=true;
return fin;
}
class BUFFER
{
protected:
char Buffer[50];
BUFFER *next;
BUFFER *front;
public:
BUFFER();
~BUFFER();
bool linkto(BUFFER&);
friend istream&operator>>(istream&,BUFFER&);
friend ostream&operator<<(ostream&,BUFFER&);
friend ifstream&operator>>(ifstream&,BUFFER&);
friend ofstream&operator<<(ofstream&,BUFFER&);
friend class makesecorytext;
};
BUFFER::BUFFER()
{
next=NULL;
front=NULL;
}
BUFFER::~BUFFER()
{
BUFFER *This;
This=this;
if(This->front==NULL)//只能让第一个成员去释放空间
{
while(This->next!=NULL)
{
This=This->next;
}
while(This->front!=NULL)
{
if(This->next!=NULL)
{
delete This->next;
}
This=This->front;//传到上一个
}
if(This->next!=NULL)//删除最后一个
{
delete This->next;
}
}
}
bool BUFFER::linkto(BUFFER&aa)
{
next=&aa;
aa.front=this;
return true;
}
istream&operator>>(istream&stin,BUFFER&aa)
{
cout<<"请输入字符串(50个字符以内)"<<endl;
stin>>setw(49)>>aa.Buffer;
return stin;
}
ostream&operator<<(ostream&stout,BUFFER&aa)
{
stout<<aa.Buffer;
return stout;
}
ifstream&operator>>(ifstream&fin,BUFFER&aa)
{
fin>>setw(49)>>aa.Buffer;
return fin;
}
ofstream&operator<<(ofstream&fout,BUFFER&aa)
{
fout<<aa.Buffer;
return fout;
}

class makesecorytext
{
char filename[20];//加密或解密的文件名
int scory;//密码,初始化为0
bool whether;//判断文件是否加密
BUFFER first;//作为缓冲内存
public:
makesecorytext();
~makesecorytext();
bool readtext();
bool secoryorbreaktext(int);//加密或解密
bool savetext();
bool display();
};
makesecorytext::makesecorytext()
{
whether=true;
filename[0]=0;
this->scory=0;
}
makesecorytext::~makesecorytext()
{
}
bool makesecorytext::readtext()
{
BUFFER *This;
This=&first;
ifstream fin;
int i=0;
system("cls");
cout<<"/n/n/n/t/t请输入要读取的文件/n/n/t/t";
cin>>filename;
fin.open(filename,ios::nocreate);
if(fin.fail())
{
cout<<"/n/n/t/t打开文件失败!!!"<<endl;
cout<<"/n/t/t";
system("PAUSE");
return false;
}
if(fin.eof())
{
cout<<"/n/n/t/t打开的是空文件!!!/n/n/t/t";
system("PAUSE");
fin.close();
return false;
}
while(!fin.eof())
{
fin>>(*This);
if(!fin.eof())
This->next=new BUFFER();
else
break;
if(This->next==NULL)
{
cout<<"/n/n/t/t计算机内存不够,读文件失败!!!"<<endl;
system("PAUSE");
fin.close();
return false;
}
This->linkto(*This->next);
This=This->next;
}
fin.close();
return true;
}
bool makesecorytext::secoryorbreaktext(int se)
{
char a=0;
char FIlename[20];
int i=0,k=0,SECORY;
BUFFER *This;
ifstream filein;
filein.open("secory.txt",ios::nocreate);
if(filein.fail())
{
cout<<"/n/n/t/t无法进行加密解密设置!!!"<<endl;
system("PAUSE");
return false;
}
This=&this->first;
if(se==0)//表示加密
{
for(;a!='1'&&a!='2';)
{
system("cls");
cout<<"/n/n/t/t请选择加密的强度:/n"
<<"/n/t/t1:普通加密/t2:密码加密"<<endl;
a=getch();
switch(a)
{
case '1':scory=0;break;
case '2':cout<<"/n/t/t请输入口令:"<<endl;//设置加密的密码,
cin>>scory;break;
default:cout<<"/n/n/t/t输入有误,重新输入!!!"<<endl;break;
}
whether=true;//表示加密了
}
}
if(se==1)//表示开始解密
{
cout<<"请输入口令:"<<endl;
cin>>SECORY;
for(;!filein.eof();)
{
filein>>FIlename>>this->scory;
filein>>whether;
cout<<FIlename;
if(strcmp(FIlename,filename)==0&&SECORY==scory)
{
k=1;
break;
}
}
filein.close();
if(k==0)
{
cout<<"输入的口令不正确或此文件没有加密!!!"<<endl;
system("PAUSE");
return false;
}
if(whether==false)
{
cout<<"文件没有加密!!!"<<endl;
system("PAUSE");
return false;
}
whether=false;//表示解密了
}
if(scory==0)
{

while((This->next)!=NULL)//开始加密
{
for(i=0;i<49&&(This->Buffer[i])!=0;i++)//因为读文件时确保了最后一个元素为字NULL符
{
This->Buffer[i]=~(This->Buffer[i]);
}
This=This->next;//把指针移到下一个
}
for(i=0;i<49&&(This->Buffer[i])!=0;i++)
{
This->Buffer[i]=~(This->Buffer[i]);
}
}
else
{
a=(this->scory)%255;
while((This->next)!=NULL)//开始加密
{
for(i=0;i<49&&(This->Buffer[i])!=0;i++)//因为读文件时确保了最后一个元素为字NULL符
{
This->Buffer[i]=(This->Buffer[i])^a;
}
This=This->next;//把指针移到下一个
}
for(i=0;i<49&&(This->Buffer[i])!=0;i++)
{
This->Buffer[i]=(This->Buffer[i])^a;
}
this->whether=true;
}

if(se==0)
cout<<"/t/t完成文件加密"<<endl;
else
cout<<"/t/t完成文件解密"<<endl;
system("PAUSE");
return true;
}
bool makesecorytext::savetext()
{
ofstream fout,fileout;
BUFFER *This;
This=&this->first;
fileout.open("secory.txt",ios::nocreate,ios::app);
if(fileout.fail())
{
cerr<<"存放密码的文件不存在或出问题,保存文件失败!!!";
system("PAUSE");
return false;
}
fileout<<endl<<filename<<" "<<scory<<" "<<whether;
fout.open(filename,ios::nocreate);
if(fout.fail())
{
cout<<"打开文件失败,加密失败并可能破坏原文件!!!"<<endl;
system("PAUSE");
return false;
}
while((This->next)!=NULL)
{
fout<<endl<<This->Buffer;
This=This->next;
}
fout<<endl<<This->Buffer;
cout<<"/t/t文件已保存"<<endl;
system("PAUSE");
fout.close();
fileout.close();
return true;
}
bool makesecorytext::display()
{
BUFFER *This;
This=&this->first;
if(strlen(This->Buffer)==0)
{
cout<<"/t/t没有内容显示!!!"<<endl;
system("PAUSE");
return false;
}
while(This->next!=NULL)
{
cout<<This->Buffer<<endl;
This=This->next;
}
cout<<This->next<<endl;
cout<<"/n/n/t/t显示了全部内容"<<endl;
system("PAUSE");
return true;
}
void main()
{
char a,cho;
bool res;
makesecorytext filesecory;
for(;;)
{
system("cls");
cout<<"/n/n/n/t/t*------------------------------------------*/n"
<<"/t/t* 欢迎进入文件加密解密处理系统 */n"
<<"/t/t*------------------------------------------*/n"
<<"/n/t/t*请选择加密还是解密:/n"
<<"/n/t/t*1:加密 2:解密"
<<"/n/n/t/t*退出请按回车键"
<<endl;
a=getch();
if(a=='1'||a=='2')
{
res=filesecory.readtext();
for(;;)
{
cout<<"/t/t是否显示文件内容(y/n)"<<endl;
cho=getch();
if(cho=='Y'||cho=='y')
{
filesecory.display();
break;
}
else if(cho=='n'||cho=='N')
break;
}
}
if(a=='1')
{
try
{
res=filesecory.secoryorbreaktext(0);
res=filesecory.savetext();
if(res==false)
throw false;
for(;;)
{
cout<<"/t/t是否显示文件内容(y/n)"<<endl;
cho=getch();
if(cho=='Y'||cho=='y')
break;
else if(cho=='n'||cho=='N')
break;
}
}
catch(bool=false)
{
cout<<"操作出错,无法继续进行!!!"<<endl;
}
}
else if(a=='2')
{
filesecory.secoryorbreaktext(1);
res=filesecory.savetext();
for(;;)
{
cout<<"/t/t是否显示文件内容(y/n)"<<endl;
cho=getch();
if(cho=='Y'||cho=='y'||cho=='n'||cho=='N')
break;
}
}
else if(a==13)
break;
else
cout<<"输入有误!!!"<<endl;
if(cho=='y'||cho=='Y')
res=filesecory.display();
}
return;
}