RSA Strings

[Atton Mathews]

I must ask how could it be possible to create RSA keys then write them to file, then read them as a string and use them in the following code.

void rsaEncode()
{
    ////////////////////////////////////////////////
    // Generate keys
    AutoSeededRandomPool rng;

    InvertibleRSAFunction params;
    params.GenerateRandomWithKeySize( rng, 1536 );

    RSA::PrivateKey privateKey( params );
    RSA::PublicKey publicKey( params );

    string plain="RSA Encryption", cipher, recovered;

    ////////////////////////////////////////////////
    // Encryption
    RSAES_OAEP_SHA_Encryptor e( publicKey );

    StringSource ss1( plain, true,
        new PK_EncryptorFilter( rng, e,
            new StringSink( cipher )
        ) // PK_EncryptorFilter
     ); // StringSource
    cout << cipher << endl;
    ////////////////////////////////////////////////
    // Decryption
    RSAES_OAEP_SHA_Decryptor d( privateKey );

    StringSource ss2( cipher, true,
        new PK_DecryptorFilter( rng, d,
            new StringSink( recovered )
        ) // PK_DecryptorFilter
     ); // StringSource

    assert( plain == recovered );
    cout << recovered << endl;
    system("pause");
}

[Jeffrey Walton]

On Wednesday, July 8, 2015 at 2:09:58 AM UTC-4, Atton Mathews wrote:

I must ask how could it be possible to create RSA keys then write them to file, then read them as a string and use them in the following code...

See http://www.cryptopp.com/wiki/Keys_and_Formats and then come back with questions :)

The short answer is to do a privateKey.Load(...) and privateKey.Save(...). The page above will help you fill in the blanks for the ellipses.

*If* you want to save them in PEM format (as opposed to ASN.1/DER), see http://www.cryptopp.com/wiki/PEM_Pack).

Jeff

[Atton Mathews]

I've seen what you are talking about, but I am talking about RSA that works like the following AES.

void EEencode (string data,string Skey)
{
    byte key[16];
    byte iv[16];
    string bin;
    string theKey(Skey);
    int i(0);
    theKey.append("t;rke;tlrke65409654ytr");

    while(i != 16)
    {
        key[i] = theKey[i];
        iv[i] = theKey[i];
        i++;
    }
    // Encryptor
    CryptoPP::ECB_Mode< CryptoPP::AES >::Encryption
    //Encryptor( key, sizeof(key), iv );
    Encryptor( key, sizeof(key));
 
  // Encryption
  CryptoPP::StringSource( data, true,
    new CryptoPP::StreamTransformationFilter( Encryptor,
      new CryptoPP::StringSink( MTbuffer )
    ) // StreamTransformationFilter
  ); // StringSource

}

[Jean-Pierre Münch]

One reasons I see why this should fail is that you defined Encryptor to be AES-ECB encryption which needs padding mechanisms to handle arbitrary data amounts. I'd suggest you to give CTR_Mode<> a try (with IV)

BR

JPM

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