如何用C#的方式实现以下PHP代码

[liangzhiweiaa]

global $ecshipPassword,$integratorUsername,$ApiServer,$ecshipUsername;

// Creating date using yyyy-mm-ddThh:mm:ssZ format
$tm_created = gmdate('Y-m-d\TH:i:s\Z');
$tm_expires = gmdate('Y-m-d\TH:i:s\Z', gmdate('U') + 180);


// Generating, packing and encoding a random number
$simple_nonce = mt_rand();
$encoded_nonce = base64_encode(pack('H*', $simple_nonce));

$passdigest = base64_encode(pack('H*',sha1(pack('H*', $simple_nonce) . pack('a*', $tm_created) . pack('a*', $ecshipPassword))));

// Initializing namespaces
$ns_wsse = 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd';
$ns_wsu = 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd';
$password_type = 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordDigest';
$encoding_type = 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-soap-message-security-1.0#Base64Binary';

// Creating WSS identification header using SimpleXML
$root = new SimpleXMLElement('<root/>');

$security = $root->addChild('wsse:Security', null, $ns_wsse);

$usernameToken = $security->addChild('wsse:UsernameToken', null, $ns_wsse);
$usernameToken->addChild('wsse:Username', $integratorUsername, $ns_wsse);
$usernameToken->addChild('wsse:Password', $passdigest, $ns_wsse)->addAttribute('Type', $password_type);
$usernameToken->addChild('wsse:Nonce', $encoded_nonce, $ns_wsse)->addAttribute('EncodingType', $encoding_type);
$usernameToken->addChild('wsu:Created', $tm_created, $ns_wsu);

// Recovering XML value from that object
$root->registerXPathNamespace('wsse', $ns_wsse);
$full = $root->xpath('/root/wsse:Security');
$auth = $full[0]->asXML();

$objSoapVarWSSEHeader = new SoapHeader($ns_wsse, 'Security', new SoapVar($auth, XSD_ANYXML), true);
$client = new SoapClient( $ApiServer . $url);
$client->__setSoapHeaders(array($objSoapVarWSSEHeader));

$objResponse = $client->__soapCall($operation,array($params));