基于Crypto++/Cryptopp的rsa密钥生成，rsa加密、解密，rsa签名、验签

4.生成rsa公钥、私钥，经过base64编码后保存到文件
需要导入一些头文件：

#include "iterhash.h"
#include "files.h"
#include "rsa.h"
#include "randpool.h"
#include "hex.h"
#include "base64.h"
#include "osrng.h"

void CKeyController :: GenerateRSAKey ( unsigned  int keyLength, CString decFilename, CString encFilename, CString seed )
{
    RandomPool randPool ;
    randPool. Put ( (byte  * )seed. GetBuffer (seed. GetLength ( ) ), seed. GetLength ( ) ) ;

    RSAES_OAEP_SHA_Decryptor decrypt (randPool, keyLength ) ;
    HexEncoder decFile ( new Base64Encoder ( new FileSink (decFilename. GetBuffer (decFilename. GetLength ( ) ) ) ) ) ;

    decrypt. DEREncode (decFile ) ;
    decFile. MessageEnd ( ) ;

    RSAES_OAEP_SHA_Encryptor encrypt (decrypt ) ;
    HexEncoder encFile ( new Base64Encoder ( new FileSink (encFilename. GetBuffer (encFilename. GetLength ( ) ) ) ) ) ;
    encrypt. DEREncode (encFile ) ;

    encFile. MessageEnd ( ) ;

     return ;
}
RandomPool  & CKeyController :: GlobalRNG ( )
{
     static RandomPool randomPool ;
     return randomPool ;
}

5.通过生成的公钥文件加密字符串

CString CKeyController :: RSAEncryptString ( CString encFilename, CString seed, CString message  )
{
    string encString ;
    FileSource encFile ( encFilename. GetBuffer (encFilename. GetLength ( ) ),  true,  new Base64Decoder ( new StringSink (encString ) )  ) ;
    HexDecoder decoder ;
    decoder. Put (  (byte * )encString. c_str ( ), encString. size ( )  ) ;
    decoder. MessageEnd ( ) ;

    RSAES_OAEP_SHA_Encryptor enc ;
    enc. AccessKey ( ). Load (decoder ) ;

    RandomPool randPool ;
    randPool. Put (  (byte  * )seed. GetBuffer (seed. GetLength ( ) ), seed. GetLength ( )  ) ;

    string result ;
    StringSource ( c2s (message ),  true,  new PK_EncryptorFilter (randPool, enc,  new HexEncoder ( new StringSink (result ) ) )  ) ;

     return CString (result. c_str ( ) ) ;
}

6.通过生成的私钥文件解密字符串

CString CKeyController :: RSADecryptString ( CString decFilename, CString ciphertext  )
{
    string decString ;
    FileSource decFile ( decFilename. GetBuffer (decFilename. GetLength ( ) ),  true,  new Base64Decoder ( new StringSink (decString ) )  ) ;
    HexDecoder decoder ;
    decoder. Put (  (byte * )decString. c_str ( ), decString. size ( )  ) ;
    decoder. MessageEnd ( ) ;

    RSAES_OAEP_SHA_Decryptor dec ;
    dec. AccessKey ( ). Load (decoder ) ;

    string result ;
    StringSource ( c2s (ciphertext ),  true,  new HexDecoder ( new PK_DecryptorFilter (GlobalRNG ( ), dec,  new StringSink (result ) ) )  ) ;

     return CString (result. c_str ( ) ) ;
}

7.使用私钥签名

CString CKeyController :: SignMessage (  const std :: string & privateKeyFileName,  const std :: string & message  )
{
    std :: string signedMessage  =  "" ;
    string encString ;
    FileSource privFile ( privateKeyFileName. c_str ( ),  true,  new Base64Decoder ( new StringSink (encString ) ) ) ;
    RSASSA_PKCS1v15_SHA_Signer priv ;

    HexDecoder decoder ;
    decoder. Put (  (byte * )encString. c_str ( ), encString. size ( )  ) ;
    decoder. MessageEnd ( ) ;

    priv. AccessKey ( ). Load (decoder ) ;

    AutoSeededRandomPool rng ;
    StringSource s1 (message,  true,  new SignerFilter (rng, priv,  new HexEncoder ( new StringSink (signedMessage ) ) ) ) ;
    
     return CString (signedMessage. c_str ( ) ) ;
}

8.使用公钥验证签名

bool CKeyController :: VerifySignature (  const std :: string & publicKeyFileName,  const std :: string & message,  const std :: string & signedMessage  )
{
    string decString ;
    FileSource pubFile ( publicKeyFileName. c_str ( ),  true,  new Base64Decoder ( new StringSink (decString ) )  ) ;
    RSASSA_PKCS1v15_SHA_Verifier pub ;

    HexDecoder decoder ;
    decoder. Put (  (byte * )decString. c_str ( ), decString. size ( )  ) ;
    decoder. MessageEnd ( ) ;

    pub. AccessKey ( ). Load (decoder ) ;

    StringSource signatureFile ( signedMessage,  true,  new HexDecoder ) ;
     if  (signatureFile. MaxRetrievable ( )  ! = pub. SignatureLength ( ) )
     {  throw std :: string (  "Signature Size Problem"  ) ;  }

    SecByteBlock signature (pub. SignatureLength ( ) ) ;
    signatureFile. Get (signature, signature. size ( ) ) ;

    VerifierFilter  *verifierFilter  =  new VerifierFilter (pub ) ;
    verifierFilter - >Put (signature, pub. SignatureLength ( ) ) ;
    StringSource s (message,  true, verifierFilter ) ;

     return verifierFilter - >GetLastResult ( ) ;
}

9.测试函数调用

void CKeyController :: testRSA ( )
{
    CString encryptKey  = _T ( "key.pub" ) ;
    CString decryptKey  = _T ( "key.pri" ) ;
    CString seed  = _T ( "seed" ) ;

     //GenerateRSAKey( 1024, decryptKey, encryptKey, seed );

    CString message  = _T ( "X3BA-9NSF-8N9Q-UWQC-U7FX-AZZF-JAJW" ) ;

    CString encryptedText  = RSAEncryptString ( encryptKey, seed, message  ) ;

    CString decryptedText  = RSADecryptString ( decryptKey, encryptedText  ) ;
    
    CString signedMessage  = SignMessage ( "key.pri", c2s (decryptedText ) ) ;

     bool verified  = VerifySignature ( "key.pub", c2s (message ), c2s (signedMessage ) ) ;
}

10.工具函数如base64转码，字符串转换

std :: string CKeyController :: EncodeBase64 ( string message  )
{
    string encode ;
    StringSource (message,  true,  new Base64Encoder ( new StringSink (encode ) ) ) ;
     return encode ;
}

std :: string CKeyController :: DecodeBase64 ( string message  )
{
    string decode ;
    StringSource (message,  true,  new Base64Decoder ( new StringSink (decode ) ) ) ;
     return decode ;
}

CString CKeyController :: hashString ( CString message  )
{
    string digest ;
    SHA256 hash ;
    StringSource foo (c2s (message ),  true,  new HashFilter (hash,  new HexEncoder ( new StringSink (digest ) ) ) ) ;
     return CString (digest. c_str ( ) ) ;
}

CString CKeyController :: hashFile ( CString fileName  )
{
    string digest ;
    SHA256 hash ;
    FileSource (fileName,  true,  new HashFilter (hash,  new HexEncoder ( new StringSink (digest ) ) ) ) ;
     return CString (digest. c_str ( ) ) ;
}

std :: string c2s ( CString  &cs  )
{
    CT2CA pszConvertedAnsiString (cs ) ;
    std :: string strStd (pszConvertedAnsiString ) ;
     return strStd ;
}