Encrypt big char* using std::string with Crypto++ - c++

Question

I am new with Crypto++. I want to using Crypto++ library to encrypt/decrypt a large byte array in C++. The data can be anything, so asume its binary format.
First, I tried with "byte array" (char * or char[]).
byte PlainText[] = {
'H','e','l','l','o',' ',
'W','o','r','l','d',
0x0,0x0,0x0,0x0,0x0
};
byte key[ AES::DEFAULT_KEYLENGTH ];
::memset( key, 0x01, AES::DEFAULT_KEYLENGTH );
// Encrypt
ECB_Mode< AES >::Encryption Encryptor( key, sizeof(key) );
byte cbCipherText[AES::BLOCKSIZE];
Encryptor.ProcessData( cbCipherText, PlainText, sizeof(PlainText) );
We use ProcessData() to encrypt the plain text, since it allows us to receive the result in a single line of code. Next, we enter a DMZ, and then decrypt the cipher text.
// Decrypt
ECB_Mode< AES >::Decryption Decryptor( key, sizeof(key) );
byte cbRecoveredText[AES::BLOCKSIZE];
Decryptor.ProcessData( cbRecoveredText, cbCipherText, sizeof(cbCipherText) );
The code above work perfect with small data (16KB). But it doesn't work with large data because "is not multiple of block size". Then, I think about using StreamTransformationFilter, which can automatic do the padding job for me. So I tried to encrypt and decrypt a std::string with encryptString() and decryptString() like below:
string encryptString(string plain, byte key[], int sizeKey, byte iv[], int sizeIV){
string cipher;
try{
CBC_Mode< AES >::Encryption e;
e.SetKeyWithIV(key, sizeKey, iv, sizeIV);
// The StreamTransformationFilter removes
// padding as required.
StringSource s(plain, true,
new StreamTransformationFilter(e,
new StringSink(cipher)
) // StreamTransformationFilter
); // StringSource
#if 0
StreamTransformationFilter filter(e);
filter.Put((const byte*)plain.data(), plain.size());
filter.MessageEnd();
const size_t ret = filter.MaxRetrievable();
cipher.resize(ret);
filter.Get((byte*)cipher.data(), cipher.size());
#endif
return cipher;
}
catch (const CryptoPP::Exception& e)
{
cerr << e.what() << endl;
return NULL;
}
}
string decryptString(string cipher, byte key[], int sizeKey, byte iv[], int sizeIV){
string reco;
try{
CBC_Mode< AES >::Decryption d;
d.SetKeyWithIV(key, sizeKey, iv, sizeIV);
StringSource s(cipher, true,
new StreamTransformationFilter(d,
new StringSink(reco)
) // StreamTransformationFilter
); // StringSource
#if 0
StreamTransformationFilter filter(e);
filter.Put((const byte*)plain.data(), plain.size());
filter.MessageEnd();
const size_t ret = filter.MaxRetrievable();
cipher.resize(ret);
filter.Get((byte*)cipher.data(), cipher.size());
#endif
return reco;
}
catch (const CryptoPP::Exception& e)
{
cerr << e.what() << endl;
return reco;
}
}
They are worked for large text file too. But, wait, my goal is encrypt/decrypt ANY byte array. And sometime they aren't string.
So I think about wrap the above two function to work with char *.
//wrap encryptString()
char* encrypt(char * plainText, byte key[], int sizeKey, byte iv[], int sizeIV){
string cipher = encryptString(plainText, key, sizeKey, iv, sizeIV);
FileUtil::writeFile("ss1.txt", cipher, cipher.length());
long len = cipher.size() + 1;
char * writable = new char[len];
std::copy(cipher.begin(), cipher.end(), writable);
writable[len] = '\0';
// don't forget to free the string after finished using it
//delete[] writable;
return writable;
}
//wrap decryptString()
char* decrypt(char * cipher, byte key[], int sizeKey, byte iv[], int sizeIV){
long len = strlen(cipher);
string recovered = decryptString(cipher, key, sizeKey, iv, sizeIV);
char * writable = new char[recovered.size() + 1];
std::copy(recovered.begin(), recovered.end(), writable);
writable[recovered.size()] = '\0'; // don't forget the terminating 0
// don't forget to free the string after finished using it
//delete[] writable;
return writable;
}
The result is:
When I read 1MB of text to encrypt() function, write the encrypted string "cipher" to "ss1.txt", its 1MB too. But to "writable", its only a part of "cipher" (about 1KB), and decrypted result is a part of original text too. Seem like '\0' was met somewhere and its terminated my char array?
I feel like going around now. Is there a way to using Crypto++ with (any) large byte (binary) array?
Additionally, I want to avoid using FileSource (Crypto++), because it doesn't allow me to save the encrypted value to variable.