sub authenticate {
 my $self = shift;
 my $q = shift;
 
 # Using Net::LDAP::Simple
 my $ldap = Net::LDAP::Simple->new( 
 		host=>$ldaphost ,
		base=>$self->{ldap}{userbase} ,
		searchattrs=>'uid'	
 
 ) or die "LDAP Connection error";
 
 my $user = $q->param('username');
 my $result = $ldap->simplesearch( $user );
 die $ldap->error unless $result;
 $ldap->unbind;
 
 my $entry = shift @{$result};

 # Bailout if user does not exist in LDAP. 
 return undef unless ($entry);
  
 my $ldaphash = $entry->get_value('userPassword');
 my $ldapuser = $entry->get_value('uid');
 
 my $md5 = Digest::MD5->new;
 $md5->add( $q->param('phrase') );
 my $hash = '{MD5}' . encode_base64($md5->digest, '');
 
 if ( ( $q->param('username') eq $ldapuser) and ($hash eq $ldaphash) )
  {
   my $sessionid = $self->start_session( $q );
   return $sessionid;
  }
 else {
  return undef
 }
}