Crypto++ 을 이용한 암호화/복호화 예제

출처: https://lyb1495.tistory.com/25

가끔 텍스트 파일을 감추고 싶을때.. 이용하면 좋음.

#include <iostream>
#include <iomanip>
 
#include "cryptopp/cryptlib.h"
#include "cryptopp/modes.h"
#include "cryptopp/aes.h"
#include "cryptopp/filters.h"
#include "cryptopp/base64.h"
 
void hex2byte(const char *in, uint len, byte *out)
{
    for (uint i = 0; i < len; i+=2) {
        char c0 = in[i+0];
        char c1 = in[i+1];
        byte c = (
            ((c0 & 0x40 ? (c0 & 0x20 ? c0-0x57 : c0-0x37) : c0-0x30)<<4) |
            ((c1 & 0x40 ? (c1 & 0x20 ? c1-0x57 : c1-0x37) : c1-0x30))
            );
        out[i/2] = c;
    }
}
 
int main(int argc, char* argv[]) {
    // 키 할당
    byte key[CryptoPP::AES::DEFAULT_KEYLENGTH];
    memset(key, 0x00, CryptoPP::AES::DEFAULT_KEYLENGTH );
    char* rawKey="f4150d4a1ac5708c29e437749045a39a";
    hex2byte(rawKey, strlen(rawKey), key);
 
    // 초기벡터 할당
    byte iv[CryptoPP::AES::BLOCKSIZE];
    memset(iv, 0x00, CryptoPP::AES::BLOCKSIZE );
    char* rawIv="86afc43868fea6abd40fbf6d5ed50905";
    hex2byte(rawIv, strlen(rawIv), iv);
 
    // 평문 할당
    std::string plaintext = "http://sopt.org/";
    std::string ciphertext;
    std::string base64encodedciphertext;
    std::string decryptedtext;
    std::string base64decryptedciphertext;
 
    // 평문 출력
    std::cout << "Plain Text (" << plaintext.size() <<
        " bytes)" << std::endl;
    std::cout << plaintext;
    std::cout << std::endl << std::endl;
 
    unsigned int plainTextLength = plaintext.length();
 
    // AES 암호화 수행
    CryptoPP::AES::Encryption
        aesEncryption(key, CryptoPP::AES::DEFAULT_KEYLENGTH);
    CryptoPP::CBC_Mode_ExternalCipher::Encryption
        cbcEncryption(aesEncryption, iv);
 
    CryptoPP::StreamTransformationFilter
        stfEncryptor(cbcEncryption, new CryptoPP::StringSink( ciphertext));
    stfEncryptor.Put(reinterpret_cast<const unsigned="" char*="">
        (plaintext.c_str()), plainTextLength + 1);
    stfEncryptor.MessageEnd();
 
    // Base64 인코딩
    CryptoPP::StringSource(ciphertext, true,
        new CryptoPP::Base64Encoder(
        new CryptoPP::StringSink(base64encodedciphertext)
        ) // Base64Encoder
        ); // StringSource
 
    // Base64 인코딩 문자열 출력
    std::cout << "Cipher Text (" << base64encodedciphertext.size()
        << " bytes)" << std::endl;
    std::cout << "cipher : " << base64encodedciphertext << std::endl;
    std::cout << std::endl << std::endl;
 
    // Base64 디코딩
    CryptoPP::StringSource(base64encodedciphertext, true,
        new CryptoPP::Base64Decoder(
        new CryptoPP::StringSink( base64decryptedciphertext)
        ) // Base64Encoder
        ); // StringSource
 
    // AES 복호화
    CryptoPP::AES::Decryption aesDecryption(key,
        CryptoPP::AES::DEFAULT_KEYLENGTH);
    CryptoPP::CBC_Mode_ExternalCipher::Decryption
        cbcDecryption(aesDecryption, iv );
 
    CryptoPP::StreamTransformationFilter
        stfDecryptor(cbcDecryption, new CryptoPP::StringSink(decryptedtext));
    stfDecryptor.Put( reinterpret_cast<const unsigned="" char*="">
        (base64decryptedciphertext.c_str()), base64decryptedciphertext.size());
    stfDecryptor.MessageEnd();
 
    // 복호화 문자열 출력
    std::cout << "Decrypted Text: " << std::endl;
    std::cout << decryptedtext;
    std::cout << std::endl << std::endl;
    return 0;
}