class WSSoapClient extends SoapClient {

    private $username;
    private $password;
    /*Generates de WSSecurity header*/
    private function wssecurity_header() {

        /* The timestamp. The computer must be on time or the server you are
         * connecting may reject the password digest for security.
         */
        $timestamp = gmdate('Y-m-d\TH:i:s\Z');
        /* A random word. The use of rand() may repeat the word if the server is
         * very loaded.
         */
        $nonce = mt_rand();
        /* This is the right way to create the password digest. Using the
         * password directly may work also,but it's not secure to transmit it
         * without encryption. And anyway,at least with axis+wss4j,the nonce
         * and timestamp are mandatory anyway.
         */
        $passdigest = base64_encode(
                pack('H*',sha1(
                                pack('H*',$nonce) . pack('a*',$timestamp).
                                pack('a*',$this->password))));

        $auth = '
<wsse:Security SOAP-ENV:mustUnderstand="1" xmlns:wsse="http://docs.oasis-open.'.
'org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd">
<wsse:UsernameToken>
    <wsse:Username>'.$this->username.'</wsse:Username>
    <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-'.
'wss-username-token-profile-1.0#PasswordDigest">'.$passdigest.'</wsse:Password>
    <wsse:Nonce>'.base64_encode(pack('H*',$nonce)).'</wsse:Nonce>
    <wsu:Created xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-'.
'200401-wss-wssecurity-utility-1.0.xsd">'.$timestamp.'</wsu:Created>
   </wsse:UsernameToken>
</wsse:Security>
';

        /* XSD_ANYXML (or 147) is the code to add xml directly into a SoapVar.
         * Using other codes such as SOAP_ENC,it's really difficult to set the
         * correct namespace for the variables,so the axis server rejects the
         * xml.
         */
        $authvalues = new SoapVar($auth,XSD_ANYXML);
        $header = new SoapHeader("http://docs.oasis-open.org/wss/2004/01/oasis-".
            "200401-wss-wssecurity-secext-1.0.xsd","Security",$authvalues,true);

        return $header;
    }

    /* It's necessary to call it if you want to set a different user and
     * password
     */
    public function __setUsernameToken($username,$password) {
        $this->username = $username;
        $this->password = $password;
    }


    /* Overwrites the original method adding the security header. As you can
     * see,if you want to add more headers,the method needs to be modifyed
     */
    public function __soapCall($function_name,$arguments,$options=null,$input_headers=null,$output_headers=null) {

        $result = parent::__soapCall($function_name,$options,$this->wssecurity_header());

        return $result;
    }
}