Improved Performance of SMFREE3's RawEncrypt

The following RawEncrypt for the cyrpto++ ctil improves performance
significantly. Before, 90% of the time to encrypt was spent allocating
and copying memory (every 8 bytes written to the buffer required an
allocation and memory copy). In my tests the changes have reduced my
encryption time from 15 minutes to less than 1 minute on a 1.7MB file.
Changes are noted by // JCSH - 7/12/2000. I suspect there is a better
way to achieve the same thing (allocate the amount of memory you need in
advance rather than when needed) but this works for now.

-Jonathan
==============================================================================
Jonathan C. Schulze-Hewett        Email: [email protected]
Software Engineer                 
Information Security Corporation  Voice: 708-445-1704       
1011 W. Lake Street, Suite 212    Fax:   708-455-9705
Oak Park, IL  60301               WWW:   http://www.infoseccorp.com


void CSM_Free3::RawEncrypt(CSM_Buffer *pbufInput, CSM_Buffer
*pbufOutput,
         Filter *pCBCEncryption, int iINBlockLen)
{
   long lBlockLen;
   char *achIn=(char *)calloc(1,iINBlockLen + 1);
   char *achOut=(char *)calloc(1,iINBlockLen + 1);
   // achBuf is used for padding at end of encryption
   int getLength;

   int nBytesWriten = 0; // JCSH - 7/12/2000.
   CSM_Buffer *pTempBuf = new CSM_Buffer(pbufInput->Length() * 2); //
JCSH - 7/12/2000.


   SME_SETUP("CSM_Free3::RawEncrypt");

   // open input for reading
   SME(pbufInput->Open(SM_FOPEN_READ));

   // open output for writing
   SME(pTempBuf ->Open(SM_FOPEN_WRITE)); // JCSH - 7/12/2000.


   // read input, cbc encrypt it, and write encrypted
   // result to output WHILE we have full blocks
   while ((lBlockLen = pbufInput->cRead(&achIn[0], iINBlockLen)) ==
iINBlockLen)
   {
      // do cbc process
      pCBCEncryption->Put((const unsigned char *) &achIn[0],
iINBlockLen);
      //RWC; "->Put(...) calls
ProcessBuf(...);pCBCEncryption->ProcessBuf();
      getLength = pCBCEncryption->Get((unsigned char *) &achOut[0],
iINBlockLen);
      if (getLength)
      {
        // now, write the block to pEncryptedData

	nBytesWriten += getLength; // JCSH - 7/12/2000.
        SME(pTempBuf->Write(&achOut[0], getLength)); // JCSH -
7/12/2000.
      }
   }
      pCBCEncryption->Put((const unsigned char *) &achIn[0], lBlockLen
);
      pCBCEncryption->InputFinished();      // auto-Pad results.
      getLength = pCBCEncryption->Get((unsigned char *) &achOut[0], 
          iINBlockLen);
      if (getLength)
      {
         // write padded block to pEncryptedData
        nBytesWriten += getLength; // JCSH - 7/12/2000.

        SME(pTempBuf->Write(&achOut[0], getLength)); // JCSH -
7/12/2000.
      }

   pbufInput->Close();

   pTempBuf->Close(); // JCSH - 7/12/2000.

   pbufOutput->Open(SM_FOPEN_WRITE); // JCSH - 7/12/2000.

   pbufOutput->Write(pTempBuf->Get(), nBytesWriten); // JCSH -
7/12/2000.

   pbufOutput->Close(); // JCSH - 7/12/2000.
   delete pTempBuf; // JCSH - 7/12/2000.
   free(achIn);
   free(achOut);

   SME_FINISH_CATCH
}