(PHP Extension) Create XML Signature with External Data Reference

Demonstrates how to create an XML digital signature where the data is external. In this case, the data is a JPG file.

This example requires Chilkat v9.5.0.69 or greater.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example inserts an XML signature in the following XML:

// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <abc>
//   <xyz>
//     <jpg>
//         <name>starfish.jpg</name>
//         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
//     </jpg>
//   </xyz>
// </abc>

// The above XML is available at https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml
// First fetch the XML:

$url = 'https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml';
$http = new CkHttp();
$sbXml = new CkStringBuilder();
$success = $http->QuickGetSb($url,$sbXml);
if ($success != true) {
    print $http->lastErrorText() . "\n";
    exit;
}

// We'll use an RSA private key for signing.  
$rsaKey = new CkPrivateKey();
$success = $rsaKey->LoadPemFile('qa_data/rsa/rsaPrivKey_pkcs8.pem');
if ($success != true) {
    print $rsaKey->lastErrorText() . "\n";
    exit;
}

$xmlSigGen = new CkXmlDSigGen();

// Indicate were the Signature will be inserted:
$xmlSigGen->put_SigLocation('abc|xyz|jpg');

// Provide the RSA key to be used for signing:
$xmlSigGen->SetPrivateKey($rsaKey);

// Fetch the JPG image data.
$jpgUrl = 'https://www.chilkatsoft.com/images/starfish.jpg';
$jpgData = new CkBinData();
$success = $http->QuickGetBd($jpgUrl,$jpgData);
if ($success != true) {
    print $http->lastErrorText() . "\n";
    exit;
}

// Add the external data reference:
$xmlSigGen->AddExternalBinaryRef($jpgUrl,$jpgData,'sha256','');

// Create the XML digital signature:
$success = $xmlSigGen->CreateXmlDSigSb($sbXml);
if ($success != true) {
    print $xmlSigGen->lastErrorText() . "\n";
    exit;
}

// Examine the XML that now contains the Signature:
print $sbXml->getAsString() . "\n";

// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <abc>
//   <xyz>
//     <jpg>
//         <name>starfish.jpg</name>
//         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
//     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/><ds:Reference URI="https://www.chilkatsoft.com/images/starfish.jpg"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>AOU810yJV5Np/DnO29qpObqiTSTTCDvxGsX5ayiTYXI=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>ApHRr6nilNrzt3dLveC9zlPoSllaCMfHsbAwr+vYBPkHkJ4wD5LzDDhi1tSJZAAeTckmvSqIG3Wi0rgXQiSM644MD3coBFx4QgrY+GZ+XJJE2Y0Ye3VvaQBiRdUW3INGsW4GLubncgQk5JhuAQjo6O/GKpfEuYqUJj/6CLHLQwMPwbZ2043ykgzuPFoOZf6EydJMBAn1ORMvrpUn+zuA9UngOTGap6eWE4CeiNx23BRC2wSztbUjdCLcqXvgiYu/v0tBNaTcwy7b6+IFtwv/lNUUBUQJ/3p+aErzFn3wLeH3yeqpDCU0U6Dqu5SS1jYupcWWsLHJjYnj2066DPJi/g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:RSAKeyValue><ds:Modulus>sXeRhM55P13FbpNcXAMR3olbw2Wa6keZIHu5YTZYUBTlYWId+pNiwUz3zFIEo+0IfYR0H27ybIycQO+1IIzJofUFNMAL3tZps2OKPlsjuCPls6kXpXhv/gvhux8LrCtp4PcKWqJ6QVOZKChc7WAx40qFWzHi57ueqRTv3x0kESqGg/VjsqyTEvb55psJO2RsfhLT7+YVh3hImRM3RDaJdkTkPuOxeFyT6N7VXD09329sLuS3QkUbE9zEKDnz9X3d8dEQdJhSI9ba5fxl8R7fu8pB67ElfzFml96X1jLFtzy1pzOT5Fc4ROcaqlYckVzdBq9sxezm6MYmDBjNAcibRw==</ds:Modulus><ds:Exponent>AQAB</ds:Exponent></ds:RSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></jpg>
//   </xyz>
// </abc>
// 

?>