Zeta Components - high quality PHP components

Some uses for this filter:

• CAPTCHA tests
• security token devices (as used by banks)

• on the initial request:
  1.  // generate a token and save it in the session or in a file/database
  2.  $pattern = "1234567890abcdefghijklmnopqrstuvwxyz";
  3.  $token  = "";
  4.  for( $i = 1; $i <= 6 ; $i++ )
  5.  {
  6.      $token .= $pattern{rand( 0, 36 )};
  7.  }
  8.  $encryptedToken = sha1( $token );
  9.  
  10.  // save the $encryptedToken in the session
  11.  session_start();
  12.  $_SESSION['encryptedToken'] = $encryptedToken;
  13.  
  14.  // also generate a distorted image which contains the symbols from $token and use it

• on the follow-up request:
  1.  // load the $encryptedToken as it was generated on a previous request
  2.  session_start();
  3.  $encryptedToken = isset( $_SESSION['encryptedToken'] ) ? $_SESSION['encryptedToken'] : null;
  4.  
  5.  // also load the value entered by the user in response to the CAPTCHA image
  6.  $captcha = isset( $_POST['captcha'] ) ? $_POST['captcha'] : null;
  7.  
  8.  $credentials = new ezcAuthenticationIdCredentials( $captcha );
  9.  $authentication = new ezcAuthentication( $credentials );
  10.  $authentication->addFilter( new ezcAuthenticationTokenFilter( $encryptedToken, 'sha1' ) );
  11.  if ( !$authentication->run() )
  12.  {
  13.      // CAPTCHA was incorrect, so inform the user to try again, eventually
  14.      // by generating another token and CAPTCHA image
  15.  }
  16.  else
  17.  {
  18.      // CAPTCHA was correct, so let the user send his spam or whatever
  19.  }