S/MIME Processing

The complexity of the S/MIME format means that the few other toolkits which are available require a high level of programmer knowledge of S/MIME processing issues. In contrast Cryptlib's enveloping interface makes the process as simple as pushing raw data into an envelope and popping the processed data back out, a total of three function calls, plus one more call to add the appropriate encryption or signature key. The code to create an S/MIME signed message is as follows;

 

  CRYPT_ENVELOPE cryptEnvelope;
  int bytesCopied;

  cryptCreateEnvelope( &cryptEnvelope, CRYPT_FORMAT_SMIME );

  /* Push in the signing key */
  cryptSetAttribute( cryptEnvelope, CRYPT_ENVINFO_SIGNATURE, sigKeyContext );

  /* Push in the data and pop out the processed data */
  cryptPushData( cryptEnvelope, data, dataLength, &bytesCopied );
  cryptPushData( cryptEnvelope, NULL, 0, NULL );
  cryptPopData( cryptEnvelope, processedData, processedDataBufsize, &bytesCopied );

  cryptDestroyEnvelope( cryptEnvelope );

To encrypt instead of signing, change the second function call to:

  /* Push in the certificate */
  cryptSetAttribute( cryptEnvelope, CRYPT_ENVINFO_PUBLICKEY, certificate );

This is all that is required. Just copy this code directly into your application to S/MIME enable it.

 

 

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