How to sign SOAP message in php - php

Question

I'm using php (yii2) and I'd like to implement SOAP communication with server. I have following guide to SOAP:
The Customer’s system uses the Customer’s private key for issuing
digital signatures. Both the application request (ApplicationRequest)
and the SOAP message must be signed separately in the WSC. The
signature is performed with the private key. The signing system must
include in the signature also the certificate. This certificate
contains the public key corresponding to the private key used in the
signing. The receiver uses the public key to authenticate the
signature.
and:
Next step: Digitally sign (detached type XML Digital Signature) the
whole SOAP message with the Private Key of Sender Certificate and put
the signature into SOAP-header
So, I have own private.key, public.key and certificate.cer
My code looks like
$client = new SoapClient($wdsl, ['trace' => true]);
$arguments = ['DownloadFileListRequest' => $dflr];
$appResponse = $client->__call('downloadFileList', $arguments);
But I get the expected error:
SOAP signature error
What I have to do and how to sign this SOAP?

Answer 1

XMLSecurityDSig helped (https://github.com/robrichards/xmlseclibs)
$dom = new DOMDocument('1.0', 'UTF-8');
$ar = $dom->createElementNS('http://bxd.fi/xmldata/', 'ApplicationRequest');
$dom->appendChild($ar);
$ar->appendChild($dom->createElement('CustomerId', $this->userID));
...
$ar->appendChild($dom->createElement('Content', $contentBase64));
$objDSig = new XMLSecurityDSig();
$objDSig->setCanonicalMethod(XMLSecurityDSig::EXC_C14N);
$objDSig->addReference(
$dom,
XMLSecurityDSig::SHA256,
['http://www.w3.org/2000/09/xmldsig#enveloped-signature'],
['force_uri' => true]
);
$objKey = new XMLSecurityKey(XMLSecurityKey::RSA_SHA256, ['type'=>'private']);
$objKey->loadKey($this->privateKeyPath, true);
$objDSig->sign($objKey);
$objDSig->add509Cert(base64_encode(file_get_contents($this->certificatePath)), false);
$objDSig->appendSignature($dom->documentElement);
$xmlRaw = $dom->saveXML();