Getting random alphabets and number in the output instead of xml

I am trying to authenticate the UIDAI API 2.5. But instead of getting response XML, I am getting random numbers and alphabets and it’s also not showing any error.

I think it is happening in the XMLdSig section, if I remove it I am not getting any output.

Also, I did not need to hit any URL to get the response so I have commented the CURL section for now

This is the documentation for better understanding of the above XML uidai.gov.in/images/resource/aadhaar_authentication_api_2_5.pdf

<?php
    require_once 'xmlseclibs/xmlseclibs.php';
    use RobRichardsXMLSecLibsXMLSecurityDSig;
    use RobRichardsXMLSecLibsXMLSecurityKey;
    
    // certificate file locations
    $public_certif = 'uidai_auth_stage.cer';
    $stag_sign_file = 'Staging_Signature_PrivateKey.p12';
    
    // set variables
    $aadhaar_no = '999999990019';
    $api_version = "2.5";
    $asa_license_key = "MMxNu7a6589B5x5RahDW-zNP7rhGbZb5HsTRwbi-VVNxkoFmkHGmYKM";
    $lk = "MBni88mRNM18dKdiVyDYCuddwXEQpl68dZAGBQ2nsOlGMzC9DkOVL5s";
    $ac = "public";
    $sa = "public";
    $tid = "public";
    $txn = "AuthDemoClient:public:".date("Ymdhms");
    $ts = date('Y-m-d').'T'.date('H:i:s');
    
    // PID Block
    $pid_block='<?xml version="1.0"?><Pid ts="'.$ts.'"><Demo><Pi ms="E" mv="100" name="Shivshankar Choudhury"/></Demo></Pid>';
    
    // generate aes-256 session key
    $session_key = openssl_random_pseudo_bytes(32);
    
    
    // generate auth xml
    $auth_xml = '<?xml version="1.0" encoding="UTF-8"?><Auth uid="'.$aadhaar_no.'" ac="'.$ac.'" lk="'.$lk.'" sa="'.$sa.'" tid="'.$tid.'" txn="'.$txn.'" ver="'.$api_version.'"><Uses bio="n" otp="n" pa="n" pfa="n" pi="y" pin="n"/><Meta fdc="NA" idc="NA" lot="P" lov="560094" pip="NA" udc="1122"/><Skey ci="'.certif_expire().'">'.encrypt_session_key($session_key).'</Skey><Data type="X">'.encrypt_pid($pid_block, $session_key).'</Data><Hmac>'.calculate_hmac($pid_block, $session_key).'</Hmac></Auth>';
    
    //echo $auth_xml;
     //die();
    // $xml=simplexml_load_string($auth_xml) or die("Error: Cannot create object");
    //print_r($xml);
    
    // xmldsig the auth xml
    $doc = new DOMDocument();
    $doc->loadXML($auth_xml);
    $objDSig = new XMLSecurityDSig();
    $objDSig->setCanonicalMethod(XMLSecurityDSig::C14N);
    $objDSig->addReference(
        $doc,
        XMLSecurityDSig::SHA256,
        array(
            'http://www.w3.org/2000/09/xmldsig#enveloped-signature',
            'http://www.w3.org/2001/10/xml-exc-c14n#'
        ),
        array('force_uri' => true)
    );
    $objKey = new XMLSecurityKey(XMLSecurityKey::RSA_SHA256, array('type'=>'private'));
    openssl_pkcs12_read(file_get_contents($stag_sign_file), $key, "public");
    $objKey->loadKey($key["pkey"]);
    $objDSig->add509Cert($key["cert"]);
    $objDSig->sign($objKey, $doc->documentElement);
    
    
    // make a request to uidai
    //$ch = curl_init("http://auth.uidai.gov.in/$api_version/public/".$aadhaar_no[0]."/".$aadhaar_no[0]."/$asa_license_key");
    //curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    //curl_setopt($ch, CURLOPT_POST, 1);
    //curl_setopt($ch, CURLOPT_POSTFIELDS, $doc->saveXML());
    //curl_setopt($ch, CURLOPT_HTTPHEADER, array(
      "Accept: application/xml",
      "Content-Type: application/xml"
    ));
    //echo "nRequest XMLn";
    echo $doc->saveXML();
    echo "nn";
    //echo "Response from UIDAIn";
    //echo htmlspecialchars_decode(curl_exec($ch));
    
    
    
    function encrypt_pid($pid_block, $session_key)
    {
        return encrypt_by_session_key($pid_block, $session_key);
    }
    
    function encrypt_by_session_key($data, $session_key)
    {
        global $public_certif;
        $data = openssl_random_pseudo_bytes(128, $cryptStrength);

        $publicKeyRes = openssl_pkey_get_public(file_get_contents($public_certif));
        $publicKeyDetails = openssl_pkey_get_details($publicKeyRes); // openssl_pkey_get_details
        $res = openssl_public_encrypt($data, $crypted, $publicKeyDetails['key']);
        $session_key = base64_encode($crypted); 
    
    }
    
    function calculate_hmac($data, $session_key)
    {
        return encrypt_by_session_key(hash('sha256', $data, true), $session_key);
    }
    
    function certif_expire()
    {
        global $public_certif;
        $certinfo = openssl_x509_parse(file_get_contents($public_certif));
        return date('Ymd', $certinfo['validTo_time_t']);
    }
    
    function encrypt_session_key($session_key)
    {
        global $public_certif;
        $pub_key = openssl_pkey_get_public(file_get_contents($public_certif));
        $keyData = openssl_pkey_get_details($pub_key);
        openssl_public_encrypt($session_key, $encrypted_session_key, $keyData['key'], OPENSSL_PKCS1_PADDING);
        return base64_encode($encrypted_session_key);
    }