Can't delete file after encrypting content with FileSource - c++

Question

I'm trying to encrypt a file using AES EAX mode and CryptoPP library.
Here is the main() content:
SecByteBlock key(AES::MAX_KEYLENGTH);
rnd.GenerateBlock(key, key.size());
ArraySource as(key.begin(), key.size(), true, new FileSink("key.bin"));
SecByteBlock iv(AES::BLOCKSIZE);
rnd.GenerateBlock(iv, AES::BLOCKSIZE);
EAX<AES>::Encryption encryptor;
encryptor.SetKeyWithIV(key, key.size(), iv, iv.size());
FileSink file("image.jpg.enc");
ArraySource write_iv(iv, iv.size(), true, new Redirector(file));
FileSource write_ciphertext("image.jpg", true, new AuthenticatedEncryptionFilter(encryptor, new Redirector(file)));
const int delete_file = std::remove("image.jpg");
std::cout << delete_file << std::endl;
std::cout << "Error code is:" << GetLastError();
return 0;
The encryption part ends successfully,however,removing the original file (image.jpg) fails.The output I get is:
Error code is:32
Which is an ERROR_SHARING_VIOLATION, meaning that "The process cannot access the file because it is being used by another process."
My question is : How can I close the file after the Filesource line,to be able to delete the file after ? With a classic ifstream ,it would be file.close(), but how can i do it with Crypto++ ?

Answer 1

I'm not familiar with crypto++ but if they're following the RAII pattern then triggering the ~FileSource destructor should be sufficient to close the handle of the file.
In C++ you would use an anonymous scope to define the lifetime of an automatic variable. Anonymous scopes are defined using curly braces without any keywords:
using namespace std;
...
encryptor.SetKeyWithIV(key, key.size(), iv, iv.size());
// begin an anonymous scope:
{
FileSink file ( "image.jpg.enc" );
ArraySource write_iv ( iv, iv.size(), true, new Redirector( file ) );
FileSource write_ciphertext ( "image.jpg", true, new AuthenticatedEncryptionFilter( encryptor, new Redirector( file ) ) );
}
// end the scope, causing all objects declared within to have their destructors called
const int delete_file = remove("image.jpg");
cout << delete_file << endl;
cout << "Error code is:" << GetLastError();
...
BTW, I noticed you use new without delete. I believe you can make those argument objects also automatic, like so:
using namespace std;
...
encryptor.SetKeyWithIV(key, key.size(), iv, iv.size());
// begin an anonymous scope:
{
FileSink file ( "image.jpg.enc" );
Redirector write_redir ( file );
ArraySource write_iv ( iv, iv.size(), true, &write_redir );
AuthenticatedEncryptionFilter filter ( encryptor, &write_redir )
FileSource write_ciphertext( "image.jpg", true, &filter );
}
// end the scope, causing all objects declared within to have their destructors called
const int delete_file = remove("image.jpg");
cout << delete_file << endl;
cout << "Error code is:" << GetLastError();
...