On Tuesday, January 3, 2017 at 11:41:44 PM UTC-5, c++programmer wrote:
>
> I've been having an issue where decrypted data is left in RAM once I'm
> done with it. I've traced the problem to decrypting the data to a
> std::string. So I've started to move all my code over to use SecByteBlock.
>
> - I wasn't able to figure out how to create a sink that put the encrypted
> data so I patched cryptolib with this:
> https://www.cryptopp.com/wiki/Secbyteblocksink
> This will come back and haunt me next time I update cryptopp so I was
> wondering if there is a better way to do it that I've missed?
> m_encrypter=new DefaultEncryptorWithMAC(blockPwd,blockPwdlen,new
> SecByteBlockSink(m_encrypteddata));
>
> - I can't find any examples of decrypting data into a SecByteBlock or
> other similar device. std::string has no guarantees of destroying its data
> afterwards so decrypted data is leaked out from the program.
>
> (Simplified version of what I'm currently doing butI need to put it into
> something other than a string)
> string decodedData;
> Filter *decrypt=new
> StringSource(m_encrypteddata.BytePtr(),m_encrypteddata.size(),true,new
> DefaultDecryptorWithMAC(blockPwd,blockPwdlen, new StringSink(decodedData)));
>
Can you use a ByteQueue? A ByteQueue is a BufferedTransformation, so it can
participate in a pipeline.
If so, then it would look similar to:
#include "queue.h"
#include "default.h"
using namespace CryptoPP;
#include <iostream>
#include <string>
using namespace std;
int main(int argc, char* argv[])
{
string password = "super secret password";
string message = "Attack at dawn!";
DefaultEncryptorWithMAC encryptor(password.c_str());
encryptor.Put((const byte*)message.data(), message.length());
encryptor.MessageEnd();
SecByteBlock encrypted(encryptor.MaxRetrievable());
encryptor.Get(encrypted, encrypted.size());
encryptor.MessageEnd();
ByteQueue decrypted;
DefaultDecryptorWithMAC decryptor(password.c_str(),
new Redirector(decrypted));
decryptor.Put(encrypted, encrypted.size());
decryptor.MessageEnd();
string recovered;
recovered.resize(decrypted.MaxRetrievable());
decrypted.Get((byte*)&recovered[0], recovered.length());
cout << recovered << endl;
return 0;
}
Jeff
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