/*!

\page mod_dcmsign dcmsign: a digital signature library and utility apps

This module contains classes to create digital signatures in DICOM data sets, to
verify and to remove signatures. Signatures are conforming to the DICOM "Digital
Signatures" extension (formerly Supplement 41). This module requires the
external OpenSSL library.

The main interface classes are:
\li \b DcmSignature
\li \b SiSecurityProfile
\li \b SiCertificate
\li \b SiPrivateKey
\li \b SiMAC

\section Tools

This module contains the following command line tool:
\li \ref dcmsign

\section Examples

The following example shows how to verify all signatures in a DICOM file:

\code
DcmFileFormat fileformat;
if (fileformat.loadFile("test.dcm").good())
{
  int counter = 0;          // counts the signatures in the DICOM file
  int corrupt_counter = 0;  // counts signatures that failed verification

  DcmDataset *dataset = fileformat.getDataset();
  DcmStack stack;           // stores current location within file
  DcmSignature signer;      // signature handler
  DcmItem *sigItem = DcmSignature::findFirstSignatureItem(*dataset, stack);
  while (sigItem) // browse through items that contain digital signatures
  {
    signer.attach(sigItem); // each item may contain multiple signatures
    for (unsigned long l=0; l < signer.numberOfSignatures(); ++l)
    {
      if (signer.selectSignature(l).good())
      {
        ++counter;
        if (signer.verifyCurrent().bad())  // verify signature
            corrupt_counter++;
      }
    }
    signer.detach();
    sigItem = DcmSignature::findNextSignatureItem(*dataset, stack);
  }
  if (counter == 0)
      cerr << "no signatures found in dataset." << endl;
  else
      cerr << counter << " signatures verified in dataset, "
           << corrupt_counter << " corrupted." << endl;
}
\endcode

The following example shows how to sign a DICOM file:

\code
DcmFileFormat fileformat;
if (fileformat.loadFile("test.dcm").good())
{
  DcmDataset *dataset = fileformat.getDataset();
  SiCreatorProfile profile;  // select the "RSA Creator Profile"
  SiRIPEMD160 mac;           // use RIPEMD160 as MAC algorithm
  DcmSignature signer;       // signature handler
  SiCertificate cert;        // our certificate
  if (cert.loadCertificate("certificate.pem", X509_FILETYPE_PEM).bad())
  {
    cerr << "unable to load certificate" << endl;
    return;
  }
  SiPrivateKey key;  // private key, must be unencrypted here
  if (key.loadPrivateKey("privkey.pem", X509_FILETYPE_PEM).bad())
  {
    cerr << "unable to load private key" << endl;
    return;
  }
  signer.attach(dataset); // connect handler to data set
  if (signer.createSignature(key, cert, mac, profile).good())
  {
    fileformat.saveFile("test_signed.dcm");  // write back
  }
}
\endcode

*/