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最近工作有个项目需要用到加密算法，在网上搜索，Crypto++库是一个不错的加密算法库，然而在网上，用Crypto++库来做ECC加密算法的例子很少。而且网上的例子也大都是把公钥和私钥生成到文件中，而笔者需要的是把公钥和私钥直接放到字符串中。
经过自己的搜索和试验，终于找到了实现的方法，可能不是最好的，但也算一种
解决方案。
关于Crypto++库的编译、安装方法，请自行度娘，这里就不累述了。
一、ECC加密算法
关于ECC加密算法的原理，请自行度娘，这里只列出算法的代码。
下面的代码已经在Windows 10、Visual Studio community 2015、Crypto++ 5.6.5环境下编译运行通过
** 在Visual Studio中编译时，需要将 "Properties -> C/C++ -> Code Generateion -> Runtime Library "改为 “Multi-threaded Debug (/MTd)”，如下图所示：**
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头文件：ecc_encryption_algorithm.h
#ifndef ECC_ENCRYPTION_ALGORITHM_H_
#define ECC_ENCRYPTION_ALGORITHM_H_
#include<string>
class EccEncryption
{
public:
/// This method is used to generate keys for ECC encryption algorithm
///
/// \param[in] uiKeySize, length of key
/// \param[out] sPrivateKey, private key
/// \param[out] sPublicKey, public key
void GenerateEccKeys(unsigned int uiKeySize, std::string& sPrivateKey, std::string& sPublicKey);
/// This method is used to encrypt the input message using public key
///
/// \param[in] sPublicKey, public key generated by the first method
/// \param[out] sMsgToEncrypt, message to encryppt
/// \return the message encrypted using the input public key
std::string Encrypt(const std::string& sPublicKey, const std::string& sMsgToEncrypt);
/// This method is used to decrypt the input message using private key
///
/// \param[in] sPrivateKey, private key used to decrypt the cipher text
/// \param[in] sMsgToDecrypt, cipher text used to decrypt to get the plain text
/// \return decrypted plain text
std::string Decrypt(const std::string& sPrivateKey, const std::string& sMsgToDecrytp);
};
#endif
cpp文件： ecc_encryption_algorithm.cpp
#include "ecc_encryption_algorithm.h"
#include "eccrypto.h"
#include "osrng.h"
#include "oids.h"
#include "hex.h"
#include "filters.h"
void EccEncryption::GenerateEccKeys(unsigned int uiKeySize, std::string& sPrivateKey, std::string& sPublicKey)
{
using namespace CryptoPP;
// Random pool, the second parameter is the length of key
// 随机数池，第二个参数是生成密钥的长
AutoSeededRandomPool rnd(false, 1024);
ECIES<ECP>::PrivateKey privateKey;
ECIES<ECP>::PublicKey publicKey;
// Generate private key
// 生成私钥
privateKey.Initialize(rnd, ASN1::secp521r1());
// Generate public key using private key
// 用私钥生成密钥
privateKey.MakePublicKey(publicKey);
ECIES<ECP>::Encryptor encryptor(publicKey);
HexEncoder pubEncoder(new StringSink(sPublicKey));
encryptor.DEREncode(pubEncoder);
pubEncoder.MessageEnd();
ECIES<ECP>::Decryptor decryptor(privateKey);
HexEncoder prvEncoder(new StringSink(sPrivateKey));
decryptor.DEREncode(prvEncoder);
prvEncoder.MessageEnd();
}
std::string EccEncryption::Encrypt(const std::string& sPublicKey, const std::string& sMsgToEncrypt)
{
using namespace CryptoPP;
// If to save the keys into a file, FileSource should be replace StringSource
// 如果需要把密钥保存到文件里，可以用 FileSource
StringSource pubString(sPublicKey, true, new HexDecoder);
ECIES<ECP>::Encryptor encryptor(pubString);
// Calculate the length of cipher text
// 计算加密后密文的长度
size_t uiCipherTextSize = encryptor.CiphertextLength(sMsgToEncrypt.size());
std::string sCipherText;
sCipherText.resize(uiCipherTextSize);
RandomPool rnd;
encryptor.Encrypt(rnd, (byte*)(sMsgToEncrypt.c_str()), sMsgToEncrypt.size(), (byte*)(sCipherText.data()));
return sCipherText;
}
std::string EccEncryption::Decrypt(const std::string& sPrivateKey, const std::string& sMsgToDecrytp)
{
using namespace CryptoPP;
StringSource privString(sPrivateKey, true, new HexDecoder);
ECIES<ECP>::Decryptor decryptor(privString);
auto sPlainTextLen = decryptor.MaxPlaintextLength(sMsgToDecrytp.size());
std::string sDecryText;
sDecryText.resize(sPlainTextLen);
RandomPool rnd;
decryptor.Decrypt(rnd, (byte*)sMsgToDecrytp.c_str(), sMsgToDecrytp.size(), (byte*)sDecryText.data());
return sDecryText;
}
测试代码： test_main.h
#include "ecc_encryption_algorithm.h"
#include <iostream>
void main()
{
std::string sStrToTest = std::string("Hello world. This is an example of Ecc\
encryption algorithm of Crypto++ open source library.");
EccEncryption ecc;
std::string sPrivateKey, sPublicKey;
ecc.GenerateEccKeys(1024, sPrivateKey, sPublicKey);
std::cout << "Generated private key is : "<< std::endl;
std::cout << sPrivateKey << std::endl;
std::cout << "***********************************************************" << std::endl;
std::cout << "Generated public key is : "<< std::endl;
std::cout << sPublicKey << std::endl;
std::cout << "***********************************************************" << std::endl;
std::cout << "The message to be encrypted is : " << std::endl;
std::cout << sStrToTest << std::endl;
std::cout << "***********************************************************" << std::endl;
std::string sEncryptResult = ecc.Encrypt(sPublicKey, sStrToTest);
std::cout << "The result of encrypt is : " << std::endl;
std::cout << sEncryptResult << std::endl;
std::cout << "***********************************************************" << std::endl;
std::string sDecryptResult = ecc.Decrypt(sPrivateKey, sEncryptResult);
std::cout << "The result of decrypt is : " << std::endl;
std::cout << sDecryptResult << std::endl;
std::cout << "***********************************************************" << std::endl;
}
运行结果如下图所示：
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