使用AES和XTR-DH Crypto ++加密音频文件

Question

I've done write code for encrypt an audio file with WAV format with AES CFB mode and XTR-DH for generate secret key.

The code here

int main()
{
AutoSeededRandomPool aSRPA;
XTR_DH xtrA(aSRPA, 170, 160);

string inputfilename;
string encryptfilename;
int aesKeyLength = SHA256::DIGESTSIZE;
int defBlockSize = AES::BLOCKSIZE;
const std::string extention(".wav");

byte iv[AES::BLOCKSIZE];
aSRPA.GenerateBlock(iv, AES::BLOCKSIZE);
SecByteBlock privateA(xtrA.PrivateKeyLength());
SecByteBlock publicA(xtrA.PublicKeyLength());
SecByteBlock secretKeyA(xtrA.AgreedValueLength());
xtrA.GenerateKeyPair(aSRPA, privateA, publicA);

SecByteBlock key(SHA256::DIGESTSIZE);
SHA256().CalculateDigest(key, secretKeyA, secretKeyA.size());

cout << "file path plain text : ";
cin >> inputfilename;
cout << "file path cipher text : ";
cin >> encryptfilename;

        if (inputfilename != extention &&
            encryptfilename != extention &&
            inputfilename.size() > extention.size() &&
            encryptfilename.size() > extention.size() &&
            inputfilename.substr(inputfilename.size() - extention.size()) == 
            ".wav" &&
            encryptfilename.substr(encryptfilename.size() - 
            extention.size()) == ".wav")
        {


            CFB_Mode<AES>::Encryption cfbEncryption(key, aesKeyLength, iv);
            cfbEncryption.ProcessData((byte*)inputfilename.c_str(), 
                                      (byte*)inputfilename.c_str(), 
                                      inputfilename.length() + 1);


            FileSink file_kunci(encryptfilename.c_str());
            StringSource ss(inputfilename, true,
                new StreamTransformationFilter(cfbEncryption,
                    new Redirector(file_kunci)));
         }
}

It's work but when I read the encrypted file, it's not a wave form like an audio file. What's wrong with my code ? Is it need to convert the audio file to array of byte or something ?

Answer 1

It's not clear what you actually want as your question title and code differ, therefore I'm going to take your code as reference. To me it looks like you want to encrypt a file and decrypt it later.

Your big if block is really too much... you can do everything pretty easiely with std::filesystem .

Also you seem to be mixing things up, this can happen if you are not familiar with cipher algorithms and/or the documentation of the library itself. First you ProcessData which seems to encrypt the string in inputfilename (?).

After all, you might want to take a look into the documentation of the library and the provided samples - these already help you a lot to understand how things are handled.

Here's a working self-contained sample of encryption and decryption of a file.

#include <filesystem>

#include "..\CryptoLib\osrng.h"
#include "..\CryptoLib\modes.h"
#include "..\CryptoLib\files.h"
#include "..\CryptoLib\aes.h"

template <typename T, std::size_t N>
constexpr std::size_t FixedArraySize(T(&arr)[N])
{ return N; }

int wmain(int argv, wchar_t **args)
{
    try
    {
        using namespace CryptoPP;

        constexpr CryptoPP::byte    IV[]    = { 0xab,0x10,0x55,0x29,0x73,0xb9,0xae,0xba,0xe9,0xe9,0xe5,0x26,0x35,0x66,0x63,0x55 };
        constexpr char              key[]   = "ABCDEFGHIJKLMNOP";

        const std::string extension         = ".TEST";
        const std::string sourceFile        = __FILE__;
        const std::string destinationFile   = std::filesystem::path("Encrypted").replace_extension(extension).string();
        const std::string finalFile         = std::filesystem::path("Decrypted").replace_extension(extension).string();

        {
            CFB_Mode<AES>::Encryption encryption(reinterpret_cast<const CryptoPP::byte*>(key), FixedArraySize(key) - 1, IV);
            FileSource fsEnc(sourceFile.c_str(), true, new StreamTransformationFilter(encryption, new FileSink(destinationFile.c_str())));

            CFB_Mode<AES>::Decryption decryption(reinterpret_cast<const CryptoPP::byte*>(key), FixedArraySize(key) - 1, IV);
            FileSource fsDec(destinationFile.c_str(), true, new StreamTransformationFilter(decryption, new FileSink(finalFile.c_str())));
        }

        std::filesystem::remove(destinationFile);
        std::filesystem::remove(finalFile);
    }
    catch (const std::exception &e)
    {
        std::cout << e.what() << std::endl;
    }
}