title: require password every time CryptSignMessage() called
body: <p>We are implementing digital signatures with microsoft wincrypt in an un-managed c++ project using 
  certificates stored on a USB token.</p>
  
  <p>Everything works as expected, except when a user goes through the process multiple times they are only required to enter their certificate password the first time unless our application is closed and restarted.</p>
  
  <p>We need for the user to be challenged with their password every time they sign some data.  Is there a way to "reset" the process?</p>
  
  <pre><code>CertOpenSystemStore(NULL,"MY");
  CertEnumCertificatesInStore(); // until we find the certificate we want
  CryptSignMessage(); // this brings up the password dialog box the first time, but not again
  // edited to show closing store and freeing context
  CertCloseStore();
  CertFreeCertificateContext();
  </code></pre>
  
  <p>thank you!</p>