// This example signs data using the RSA method from a file to memory in 8K (8192 byte) chunks. 

// This code uses the #import directive.
// Put the following line at the beginning of your module

#import "XCEEDCRY.DLL" no_namespace named_guids 

CoInitialize( NULL ); 

try
{
  const long CHUNKSIZE = 8192;  

  IXceedSigningPtr piSign; 

  piSign.CreateInstance( CLSID_XceedSigning ); 
  piSign->License( _bstr_t( L"your license key ) ); 

  IXceedRSASigningMethodPtr piRSA; 

  piRSA.CreateInstance( CLSID_XceedRSASigningMethod );  

  // The following call to SetRandomKeyPair would, in the real world,  
  // be replaced by the assignment of a Private Key to the  
  // PrivateKey property.  

  piRSA->SetRandomKeyPair( 512, NULL, 0 ); 

  piSign->SigningMethod = IXceedSignDataPtr( piRSA );  

  BYTE* pcSignature = NULL; 
  short nSignatureSize; 
  DWORD dwBytesRead; 
  long lOffset = 0;  

  HANDLE hFile = CreateFile( "c:\\temp\\source.txt", 0, 
                             FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL );  

  if( hFile == INVALID_HANDLE_VALUE ) 
    throw;  

  long lFileSize = GetFileSize( hFile, NULL ); 
  CloseHandle( hFile );  

  if( lFileSize == 0xFFFFFFFF ) 
    throw;  

  while( lOffset < lFileSize ) 
  { 
    // bEndOfData will be true if the current offset + CHUNKSIZE exceeds the end of the file. 
    piSign->ReadFile( "c:\\temp\\source.txt", lOffset, CHUNKSIZE, efpSign, 
                      (lOffset + CHUNKSIZE >= lFileSize), &dwBytesRead );  

    lOffset += dwBytesRead; 
  }  

  piRSA->GetSignature( &pcSignature, &nSignatureSize );  

  //Do something with the Signature...  

  CoTaskMemFree( pcSignature );  

  MessageBox( NULL, "File signed successfully to memory", "Signing result", MB_OK );  

  lOffset = 0; 

  while( lOffset < lFileSize ) 
  { 
    // bEndOfData will be true if the current offset + CHUNKSIZE exceeds the end of the file. 
    piSign->ReadFile( "c:\\temp\\source.txt", lOffset, CHUNKSIZE, efpVerify,
                      (lOffset + CHUNKSIZE >= lFileSize), &dwBytesRead );  

   lOffset += dwBytesRead; 
  }  

  MessageBox( NULL, "Data verified successfully", "Verifying result", MB_OK ); 
}
catch( const _com_error& xErr )
{
  if( xErr.Error() == eerVerifyFailed ) 
  { 
    MessageBox( NULL, "Verification of signature failed", "Verifying result", MB_OK ); 
  } 
  else 
  { 
    char szMsg[50]; 
    wsprintf( szMsg, "Error %08x\n", xErr.Error() ); 
    MessageBox( NULL, szMsg, "Error", MB_OK ); 
  } 
}
catch( ... )
{
  MessageBox( NULL, "Unknown error", "Error", MB_OK ); 
} 

CoUninitialize();