简单实现凯撒密码的c++代码

有关信息安全的凯撒密码c++代码，其中文件输入和输出的地址可能需要大家重新编写一下

#include
#include
#include
using namespace std;

#define infinite 9999999

void encryption（stringint）;
void decryption（stringintint）;
void getFrequency（double*string）;
void crack（string）;
int main（）
{
	int key;
	string FilePath;
	int option ;   //选择项
	while（1）
	{
		cout<<“please select option number:“<		cout<<“1.encryption“<		cout<<“2.decryption“<		cout<<“3.crack“<		cout<<“4.exit“<		cin >> option;
		if（option==4） break;
		switch （option）
		{
		case 1:
			cout<<“please enter the file path:“<			cin>>FilePath;
			cout<<“please enter the key:“<			cin>>key;
			encryption（FilePathkey）;
			break;
		case 2:
			cout<<“please enter the file path:“<			cin>>FilePath;
			cout<<“please enter the key:“<			cin>>key;
			decryption（FilePathkey0）;     //0表示解密 1表示破解
			break;
		case 3:
			cout<<“please enter the file path:“<			cin>>FilePath;
			crack（FilePath）;
			break;
		}
	}
}

void encryption（string filepathint key）
{
	char character;
	ifstream inputFile（filepathios::in）;
	ofstream encrpFile（“encryption\\encryption.txt“ios::out）;
	//取单个字符分别加密
	while（!inputFile.eof（））
	{
		//inputFile>>character;
		inputFile.get（character）;
		if（character>=‘a‘&&character<=‘z‘）
		{
			character=character+key<=‘z‘?character+key:character-26+key;  //减去key小于a的aski码值+26
		}
		else if（character>=‘A‘&&character<=‘Z‘）
		{
			character=character-key>=‘Z‘?character-key:character-26+key;
		}
		encrpFile<	}
	inputFile.close（）;
	encrpFile.close（）;
}
void decryption（string filepathint keyint option）
{
	char character;
	string decryPath;
	ifstream inputFile（filepathios::in）;
	if（option==0） //解密
	{
		decryPath=“decryption\\decrption.txt“;

	}else if（option==1）
	{
		decryPath=“crack\\crack.txt“;
	}
	ofstream decryFile（decryPathios::out）;
	
	//取单个字符分别加密
	while（!inputFile.eof（））
	{
		inputFile>>character;
		if（character>=‘a‘&&character<=‘z‘）
		{
			character=character-key>=‘a‘?character-key:character+26-key;  //减去key小于a的aski码值+26
		}
		else if（character>=‘A‘&&character<=‘Z‘）
		{
			character=character-key>=‘A‘?character-key:character+26-key;
		}
		decryFile<	}
	inputFile.close（）;
	decryFile.close（）;
}
void  crack（string filepath）
{
	
	int key;
	double frequency[26]={0};
	long double temp;
	double Chi_squared=infinite;
	double expect[26]={0.081670.014920.027820.042530.127020.022280.020150.060940.069660.001530.00772
		0.040250.024060.067490.075070.019290.000950.059870.063270.090560.027580.009780.023610.001500.019740.00074};
	getFrequency（frequencyfilepath）;
	for（ int j=0;j<26;j++）
	{
		temp=0;
		for（int i=0;i<26;i++）     //卡方校验
		{
			temp+=（frequency[（i+j）%26]-expect[i]）*（frequency[（i+j）%26]-expect[i]）/expect[i];
			

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----

     文件       3226  2017-10-24 17:41  CaesarCipher\CaesarCipher\CaesarCipher.vcxproj

     文件        942  2017-10-24 17:41  CaesarCipher\CaesarCipher\CaesarCipher.vcxproj.filters

     文件        143  2017-10-24 16:14  CaesarCipher\CaesarCipher\CaesarCipher.vcxproj.user

     文件        265  2017-10-31 16:31  CaesarCipher\CaesarCipher\crack\crack.txt

     文件        381  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\CaesarCipher.exe.intermediate.manifest

     文件         67  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\CaesarCipher.lastbuildstate

     文件       2009  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\CaesarCipher.log

     文件        713  2017-10-25 20:39  CaesarCipher\CaesarCipher\Debug\CaesarCipher.vcxprojResolveAssemblyReference.cache

     文件          0  2017-10-25 20:39  CaesarCipher\CaesarCipher\Debug\CaesarCipher.write.1.tlog

     文件        560  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\cl.command.1.tlog

     文件       3954  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\CL.read.1.tlog

     文件        336  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\CL.write.1.tlog

     文件       1188  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\link.command.1.tlog

     文件       2480  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\link.read.1.tlog

     文件        604  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\link.write.1.tlog

     文件     254073  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\main.obj

     文件        468  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\mt.command.1.tlog

     文件        898  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\mt.read.1.tlog

     文件        282  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\mt.write.1.tlog

     文件     207872  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\vc100.idb

     文件     249856  2017-10-31 16:38  CaesarCipher\CaesarCipher\Debug\vc100.pdb

     文件        265  2017-10-31 16:30  CaesarCipher\CaesarCipher\decryption\decrption.txt

     文件        340  2017-10-31 16:38  CaesarCipher\CaesarCipher\encryption\encryption.txt

     文件       3796  2017-10-31 16:38  CaesarCipher\CaesarCipher\main.cpp

     文件    6377472  2017-11-14 17:53  CaesarCipher\CaesarCipher.sdf

     文件        903  2017-10-24 16:14  CaesarCipher\CaesarCipher.sln

    ..A..H.     15872  2017-11-14 17:53  CaesarCipher\CaesarCipher.suo

     文件      98816  2017-10-31 16:38  CaesarCipher\Debug\CaesarCipher.exe

     文件     666396  2017-10-31 16:38  CaesarCipher\Debug\CaesarCipher.ilk

     文件     756736  2017-10-31 16:38  CaesarCipher\Debug\CaesarCipher.pdb

............此处省略13个文件信息