使用Crypto++5.5.2完成RSA加解密,真正的把公鑰放在字串內，而不是放在檔案內

阿新 • • 發佈：2019-02-15

忙活了一週，基本完成了Crypto++庫中關於RSA加解密的API封裝！這一週裡，查了很多Crypto++的相關資料，感覺這方面的內容乏善可陳，或者太簡單，或者太籠統！本文希望能給使用Crypto++的朋友帶來一些幫助，主要還是原始碼了，實在沒有時間碼文字！在測試過程中，感覺Crypto++還是非常高效的，期待更多的人使用Crypto++。此外，Crypto++的原始碼極富研究價值，是深入學習C++的經典材料！愛好 C++的你，千萬別錯過了~

本文提供的C++原始碼已在Redhat Enterprise Server 5.0和Windows XP平臺編譯連結成功，使用的編譯器分別是g++ 3.4.6、Visual C++ 6.0 (SP 6)。由於兩個平臺的程式碼差別不大，僅提供Linux平臺的程式碼！如果你需要Windows平臺的程式碼，可以向我索取，留下你的郵件地址即可！如果你在使用過程中，遇到任何問題，也歡迎你給我留言！

源程式主要包括五個檔案：MyRSA.h、 MyRSA.cpp、Main.h、Main.cpp、makefile；兩個目錄：lib目錄包含libcryptopp.a，include目錄包含Crypto++5.5.2中的所有.h標頭檔案。對了，上述五個檔案與lib,include目錄在同一層目錄！需要說明的是，makefile是借用了一個兄弟的，忘記名字了，不好意思:-)

哈，還是貼程式碼吧!

/************************** MyRSA.h ********************************/
#ifndef __MYRSA_H__
#define __MYRSA_H__

#include <string>

#include "files.h"
#include "filters.h"
#include "hex.h"
#include "randpool.h"
#include "rsa.h"

using namespace std;
using namespace CryptoPP;

class CMyRSA
{
public:
    CMyRSA(void);
    virtual ~CMyRSA(void);

//You must set the KeyLength 512, 1024, 2048 ...
    void GenerateKey(const unsigned int KeyLength, const char *Seed, RSAES_OAEP_SHA_Decryptor &Priv, RSAES_OAEP_SHA_Encryptor &Pub);
    void GenerateKey(const unsigned int KeyLength, const char *Seed, string &strPriv, string &strPub);
    
    //use public key to encrypt
    void EncryptString(const RSAES_OAEP_SHA_Encryptor &Pub, const char *Seed, const string &Plaintext, string &Ciphertext);
    void EncryptString(const string &strPub, const char *Seed, const string &Plaintext, string &Ciphertext);

//use private key to decrypt
    void DecryptString(const RSAES_OAEP_SHA_Decryptor &Priv, const string &Ciphertext, string &Plaintext);
    void DecryptString(const string &strPriv, const string &Ciphertext, string &Plaintext);

private:
    static RandomPool & RNG(void);

private:
    static RandomPool m_sRandPool;
};

#endif /* End of __MYRSA_H__ */

/************************** MyRSA.cpp ********************************/
#include "MyRSA.h"

CMyRSA::CMyRSA()
{

}

CMyRSA::~CMyRSA(void)
{

}

void CMyRSA::GenerateKey(const unsigned int KeyLength, const char *Seed, RSAES_OAEP_SHA_Decryptor &Priv, RSAES_OAEP_SHA_Encryptor &Pub)
{
    RandomPool RandPool;
    RandPool.IncorporateEntropy((byte *)Seed, strlen(Seed));
    
    //generate private key
    Priv = RSAES_OAEP_SHA_Decryptor(RandPool, KeyLength);

//generate public key using private key
    Pub = RSAES_OAEP_SHA_Encryptor(Priv);
}

void CMyRSA::GenerateKey(const unsigned int KeyLength, const char *Seed, string &strPriv, string &strPub)
{
    RandomPool RandPool;
    RandPool.IncorporateEntropy((byte *)Seed, strlen(Seed));

//generate private key
    RSAES_OAEP_SHA_Decryptor Priv(RandPool, KeyLength);
    HexEncoder PrivateEncoder(new StringSink(strPriv));//本部落格作者加：就為了這句程式碼整整找了1天！
    Priv.DEREncode(PrivateEncoder);
    PrivateEncoder.MessageEnd();

//generate public key using private key
    RSAES_OAEP_SHA_Encryptor Pub(Priv);
    HexEncoder PublicEncoder(new StringSink(strPub));
    Pub.DEREncode(PublicEncoder);
    PublicEncoder.MessageEnd();
}

void CMyRSA::EncryptString(const RSAES_OAEP_SHA_Encryptor &Pub, const char *Seed, const string &Plaintext, string &Ciphertext)
{
    RandomPool RandPool;
    RandPool.IncorporateEntropy((byte *)Seed, strlen(Seed));

int MaxMsgLength = Pub.FixedMaxPlaintextLength();
    for (int i = Plaintext.size(), j=0; i > 0; i -= MaxMsgLength, j += MaxMsgLength)
    {
        string PartPlaintext = Plaintext.substr(j, MaxMsgLength);
        string PartCiphertext;
        StringSource(PartPlaintext, true, new PK_EncryptorFilter(RandPool, Pub, new HexEncoder(new StringSink(PartCiphertext))));
        Ciphertext += PartCiphertext;                  
    }
}

void CMyRSA::EncryptString(const string &strPub, const char *Seed, const string &Plaintext, string &Ciphertext)
{
    StringSource PublicKey(strPub, true, new HexDecoder);
    RSAES_OAEP_SHA_Encryptor Pub(PublicKey);

RandomPool RandPool;
    RandPool.IncorporateEntropy((byte *)Seed, strlen(Seed));

void CMyRSA::DecryptString(const RSAES_OAEP_SHA_Decryptor &Priv, const string &Ciphertext, string &Plaintext)
{
    //indicate the ciphertext in hexcode
    int CiphertextLength = Priv.FixedCiphertextLength() * 2;
    for (int i = Ciphertext.size(), j=0; i > 0; i -= CiphertextLength, j += CiphertextLength)
    {
            string PartCiphertext = Ciphertext.substr(j, CiphertextLength);
            string PartPlaintext;
            StringSource(PartCiphertext, true, new HexDecoder(new PK_DecryptorFilter(RNG(), Priv, new StringSink(PartPlaintext))));
            Plaintext += PartPlaintext;
    }
}

void CMyRSA::DecryptString(const string &strPriv, const string &Ciphertext, string &Plaintext)
{
    StringSource PrivKey(strPriv, true, new HexDecoder);
    RSAES_OAEP_SHA_Decryptor Priv(PrivKey);
    
    //indicate the ciphertext in hexcode
    int CiphertextLength = Priv.FixedCiphertextLength() * 2;
    for (int i = Ciphertext.size(), j=0; i > 0; i -= CiphertextLength, j += CiphertextLength)
    {
            string PartCiphertext = Ciphertext.substr(j, CiphertextLength);
            string PartPlaintext;
            StringSource(PartCiphertext, true, new HexDecoder(new PK_DecryptorFilter(RNG(), Priv, new StringSink(PartPlaintext))));
            Plaintext += PartPlaintext;
    }
}

RandomPool & CMyRSA::RNG(void)
{
    return m_sRandPool;
}

RandomPool CMyRSA::m_sRandPool;

/************************** Main.h ********************************/
#ifndef __MAIN_H__
#define __MAIN_H__

#endif /* End of __MAIN_H__ */

/************************** Main.cpp ********************************/
#include <unistd.h>

#include <iostream>

#include "Main.h"
#include "MyRSA.h"

/***** STATIC VARIABLES *****/
static RSAES_OAEP_SHA_Encryptor g_Pub;
static RSAES_OAEP_SHA_Decryptor g_Priv;
static string g_strPub;
static string g_strPriv;

int main(int argc, char *argv[])
{
    try
    {
        char Seed[1024], Message[1024], MessageSeed[1024];
        unsigned int KeyLength;
        CMyRSA MyRSA;

cout << "Key length in bits: ";
        cin >> KeyLength;

cout << "/nRandom Seed: ";
        ws(cin);
        cin.getline(Seed, 1024);

cout << "/nMessage: ";
        ws(cin);    
        cin.getline(Message, 1024);

cout << "/nRandom Message Seed: ";
        ws(cin);
        cin.getline(MessageSeed, 1024);
        
        MyRSA.GenerateKey(KeyLength, Seed, g_Priv, g_Pub);
        //MyRSA.GenerateKey(KeyLength, Seed, g_strPriv, g_strPub);

//If generate key in RSAES_OAEP_SHA_Encryptor and RSAES_OAEP_SHA_Decryptor, please note four lines below
        /*
        cout << "g_strPub = " << g_strPub << endl;
        cout << endl;
        cout << "g_strPriv = " << g_strPriv << endl;
        cout << endl;
        */
        
        string Plaintext(Message);
        string Ciphertext;
        MyRSA.EncryptString(g_Pub, MessageSeed, Plaintext, Ciphertext);
        //MyRSA.EncryptString(g_strPub, MessageSeed, Plaintext, Ciphertext);
        cout << "/nCiphertext: " << Ciphertext << endl;
        cout << endl;

string Decrypted;
        MyRSA.DecryptString(g_Priv, Ciphertext, Decrypted);
        //MyRSA.DecryptString(g_strPriv, Ciphertext, Decrypted);
        cout << "/nDecrypted: " << Decrypted << endl;
        return 0;
    }
    catch(CryptoPP::Exception const &e)
    {
        cout << "/nCryptoPP::Exception caught: " << e.what() << endl;
        return -1;
    }
    catch(std::exception const &e)
    {
        cout << "/nstd::exception caught: " << e.what() << endl;
        return -2;
    }
    return -3;
}

/************************** Makefile ********************************/
# The executable file name.
PROGRAM := myrsa

# The directories in which source files reside.
SRCDIRS := . # current directory

# The source file types (headers excluded).
SRCEXTS := .cpp

# The flags used by the cpp (man cpp for more).
CPPFLAGS :=

# The compiling flags used only for C.
# If it is a C++ program, no need to set these flags.
# If it is a C and C++ merging program, set these flags for the C parts.

CFLAGS :=

CFLAGS +=

# The compiling flags used only for C++.
# If it is a C program, no need to set these flags.
# If it is a C and C++ merging program, set these flags for the C++ parts.

CXXFLAGS := -g -O2 -I./include

CXXFLAGS +=

# The library and the link options ( C and C++ common).

LDFLAGS := -L./lib -lcryptopp

LDFLAGS +=

## Implict Section: change the following only when necessary.

##=============================================================================

# The C program compiler. Uncomment it to specify yours explicitly.

#CC = gcc

# The C++ program compiler. Uncomment it to specify yours explicitly.

CXX = g++

# Uncomment the 2 lines to compile C programs as C++ ones.

CC = $(CXX)

CFLAGS = $(CXXFLAGS)

# The command used to delete file.

RM = rm -f

## Stable Section: usually no need to be changed. But you can add more.

##=============================================================================

SHELL = /bin/sh

SOURCES = $(foreach d,$(SRCDIRS),$(wildcard $(addprefix $(d)/*,$(SRCEXTS))))

OBJS = $(foreach x,$(SRCEXTS), /
      $(patsubst %$(x),%.o,$(filter %$(x),$(SOURCES))))

DEPS = $(patsubst %.o,%.d,$(OBJS))

.PHONY : all objs clean cleanall rebuild

all : $(PROGRAM)

# Rules for creating the dependency files (.d).

#---------------------------------------------------

%.d : %.c

@$(CC) -MM -MD $(CFLAGS) $<

%.d : %.C

@$(CC) -MM -MD $(CXXFLAGS) $<

%.d : %.cc

@$(CC) -MM -MD $(CXXFLAGS) $<

%.d : %.cpp

@$(CC) -MM -MD $(CXXFLAGS) $<

%.d : %.CPP

@$(CC) -MM -MD $(CXXFLAGS) $<

%.d : %.c++

@$(CC) -MM -MD $(CXXFLAGS) $<

%.d : %.cp

@$(CC) -MM -MD $(CXXFLAGS) $<

%.d : %.cxx

@$(CC) -MM -MD $(CXXFLAGS) $<

# Rules for producing the objects.

#---------------------------------------------------

objs : $(OBJS)

%.o : %.c

$(CC) -c $(CPPFLAGS) $(CFLAGS) $<

%.o : %.C