Crypto++

梦里梦外; 2022-08-06 17:07 145阅读 0赞

Crypto++是个免费的C++加解密类库，由于资格太老、持续更新，最新版本到了CryptoPP 5.6，对天缘而言，第一眼看到CryptoPP就感觉头大，根目录下放置大量单源文件、编译文件、项目文件，再加上多平台和多编译器支持，文件几乎又多了一倍，而且还是都混到一起，直接就让人望而却步。毕竟Crypto是个功能完整，且经过大量用户使用考验的开源库。所以，皱眉学习汇总一下，遂成此文。

官方网址：[http://www.cryptopp.com/][http_www.cryptopp.com]

本文测试环境：Windows7 SP1+VC6，测试工程名为Test。用VC打开CryptoPP工程文件，会发现有四个子工程：

*  cryptdll - 生成cryptopp.dll动态库
 *  dlltest - 用来测试cryptopp.dll，依赖cryptdll工程
 *  cryptlib - 生成cryptlib.lib静态库
 *  cryptest - 用来测试cryptopp，依赖cryptlib工程

所以，我们有两种使用CryptoPP方法，一种是静态链接，还有一种是动态链接，使用对应的工程编译即可，区别就不说了，我们下文以静态链接为例，介绍几种常用加解密算法使用。

## 一、编译cryptlib ##

首先需要编译cryptlib，最后得到cryptlib.lib文件。

1.  先在测试工程Test下创建目录cryptopp\\lib和cryptopp\\include，并把Project Settings-C/C++-Processor下Include目录增加“cryptopp\\include”。
2.  把cryptlib.lib拷贝到Test\\cryptopp\\lib下。
3.  把cryptoPP根目录下所有的\*.h文件都拷贝到Test\\cryptopp\\include下。当然实际上用不了那么多，后续用到哪个include哪个。

下文开始测试使用CryptoPP，实际使用中，如果功能上逻辑上需要修改，可以参考上文测试工程中的示例程序，以及官方文档。下文编译如果报告XX重复定义等错误，请检查LIB库工程和本测试工程的：Project Setting-C/C++-Code Generation User run-time library是否统一。

## 二、测试cryptlib ##

### 1、测试MD5 ###

#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
    #include "md5.h"
    using namespace CryptoPP;
    #pragma comment(lib, "cryptopp\\lib\\cryptlib.lib") 
    
    using namespace std;
    
    void main() {
    	
    	byte message[]="HelloWorld!";       
    	byte mres[16];//MD5 128 bits=16bytes
    
    	Weak::MD5 md5; 
    	md5.Update(message,11);//strlen=11
    	md5.Final(mres);       
    	
    	for(int i=0;i<16;i++)
    		printf("%02X",mres[i]);
    	   
    	printf("\n");
    }

### 2、测试AES ###

//For AES encrypt
    #include "default.h" 
    #include "cryptlib.h"
    #include "filters.h"
    #include "bench.h"
    #include "osrng.h"
    #include "hex.h"
    #include "modes.h"
    #include "files.h"
    	
    using namespace CryptoPP;
    #pragma comment(lib, "cryptopp\\lib\\cryptlib.lib") 
    
    using namespace std;
    
    void main() {
    
    	unsigned char key[]	= {0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,	0x01,0x02, 0x03,0x04,0x05,0x06,0x07,0x08};//AES::DEFAULT_KEYLENGTH
    	unsigned char iv[]	= {0x01,0x02,0x03,0x03,0x03,0x03,0x03,0x03,	0x03,0x03, 0x01,0x02,0x03,0x03,0x03,0x03};
    	int keysize = 16;
    
    	string	message = "Hello World!";
    	string	strEncTxt;
    	string	strDecTxt;
    	
    	//CBC - PADDING
    	//AES-CBC Encrypt(ONE_AND_ZEROS_PADDING)
    	CBC_Mode<AES>::Encryption  Encryptor1(key,keysize,iv); 
    	StringSource(	message,
    					true,
    					new StreamTransformationFilter(	Encryptor1,
    						new StringSink( strEncTxt ),
    						BlockPaddingSchemeDef::BlockPaddingScheme::ONE_AND_ZEROS_PADDING,
    						true)
    			);
    	
    	//AES-CBC Decrypt
    	CBC_Mode<AES>::Decryption Decryptor1(key,keysize,iv); 
    	StringSource(	strEncTxt, 
    					true,
    					new StreamTransformationFilter( Decryptor1,
    						new StringSink( strDecTxt ),
    						BlockPaddingSchemeDef::BlockPaddingScheme::ONE_AND_ZEROS_PADDING,
    						true)
    			);
    	
    
    	//CTR - NO_PADDING
    	//AES-CTR Encrypt
    	CTR_Mode<AES>::Encryption  Encryptor2(key,keysize,iv); 
    	StringSource(	message, 
    					true,
    					new StreamTransformationFilter( Encryptor2,
    						new StringSink( strEncTxt ),
    						BlockPaddingSchemeDef::BlockPaddingScheme::NO_PADDING,
    						true)
    			); 
    	
    	//AES-CTR Decrypt
    	CTR_Mode<AES>::Decryption Decryptor2(key,keysize,iv); 
    	StringSource(	strEncTxt, 
    					true,
    					new StreamTransformationFilter( Decryptor2,
    						new StringSink( strDecTxt ),
    						BlockPaddingSchemeDef::BlockPaddingScheme::NO_PADDING,
    						true)
    			);  
    	
    }

上文是使用StringSource方式加密字符串，还可以使用FileSource方式直接对文件进行加解密操作。示例如下：

SecByteBlock HexDecodeString(const char *hex) {
    	StringSource ss(hex, true, new HexDecoder);
    	SecByteBlock result((size_t)ss.MaxRetrievable());
    	ss.Get(result, result.size());
    	return result;
    }
    
    void AES_CTR_Encrypt(const char *hexKey, const char *hexIV, const char *infile, const char *outfile) {
    	SecByteBlock key = HexDecodeString(hexKey);
    	SecByteBlock iv = HexDecodeString(hexIV);
    
    	CTR_Mode<AES>::Encryption aes(key, key.size(), iv);
    
    	FileSource(infile, true, new StreamTransformationFilter(aes, new FileSink(outfile)));
    }

直接调用AES\_CTR\_Encrypt函数即可，CBC函数需对应修改。

## 四、使用提示 ##

### 1、StringSource类定义filters.h ###

//! zero terminated string as source
    	StringSource(const char *string, bool pumpAll, BufferedTransformation *attachment = NULL)
    		: SourceTemplate<StringStore>(attachment) {SourceInitialize(pumpAll, MakeParameters("InputBuffer", ConstByteArrayParameter(string)));}
    	//! binary byte array as source
    	StringSource(const byte *string, size_t length, bool pumpAll, BufferedTransformation *attachment = NULL)
    		: SourceTemplate<StringStore>(attachment) {SourceInitialize(pumpAll, MakeParameters("InputBuffer", ConstByteArrayParameter(string, length)));}
    	//! std::string as source
    	StringSource(const std::string &string, bool pumpAll, BufferedTransformation *attachment = NULL)
    		: SourceTemplate<StringStore>(attachment) {SourceInitialize(pumpAll, MakeParameters("InputBuffer", ConstByteArrayParameter(string)));}

### 2、RSA有关的加解密、签名函数 ###

更多请参考工程cryptest工程下test.cpp文件内函数

void GenerateRSAKey(unsigned int keyLength, const char *privFilename, const char *pubFilename, const char *seed);
    string RSAEncryptString(const char *pubFilename, const char *seed, const char *message);
    string RSADecryptString(const char *privFilename, const char *ciphertext);
    void RSASignFile(const char *privFilename, const char *messageFilename, const char *signatureFilename);
    bool RSAVerifyFile(const char *pubFilename, const char *messageFilename, const char *signatureFilename);

[http_www.cryptopp.com]: http://www.cryptopp.com/