Authenticating against .htpasswd style files.

<?php
if( !($passwd = @fopen( "passwords", "r" )))
{  echo "Cannot open password file.";
   exit;
}

if( !$PHP_AUTH_USER )
{  Header( "WWW-authenticate: basic realm=\"Realm\"" );
   Header( "HTTP/1.0 401 Unauthorized" );
   echo "Text to see if user hits 'Cancel'";
   exit;
}

// file format => username:passwd{\n}
while( $pwent = fgets( $passwd, 100 ))
{  $part = split( ":", ereg_replace( "\n", "", $pwent ));
   if( $part[0] != $PHP_AUTH_USER )
      continue;

   // Username was found - verify passwd
   if( $part[1] !=
        // The crypt salt is stored as chars 1&2 of passwd
        crypt( $PHP_AUTH_PW, substr( $part[1], 0, 2 )))
      break;

   echo "Hello $PHP_AUTH_USER.<p>\n";
}

// This only has effect of no text was output previously, so
//  it is ignored in all cases except authentication error.
@Header( "HTTP/1.0 401 Unauthorized" );
?>