(PHP Extension) SII Chile - FRMA Signature Computation and Add to XML

Compute the FRMA signature of a <DA> element enclosed inside a <CAF> element of the XML to be signed.

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

// Also see:  Compute the FRMT Signature and Add to XML

$xml = new CkXml();

// Load the unsigned XML that contains the following:

// <DTE version="1.0">
//   <Documento ID="F60T33">
//         <TED version="1.0">
//             <DD>
// 		...
//                 <CAF version="1.0">
//                     <DA>
// 			...
//                     </DA>
// 			... The FRMA will be added here ...
//                 </CAF>
//                 ...
//             </DD>
//             ... The FRMT will be added here in another example ...
//         </TED>
//   </Documento>
// </DTE>

$success = $xml->LoadXmlFile('qa_data/xml_dsig/sii_cl/test_0.xml');
if ($success == false) {
    print 'Failed to load initial XML file.' . "\n";
    exit;
}

// Get a reference to the "DA" element
// daXml is a CkXml
$daXml = $xml->FindChild('Documento|TED|DD|CAF|DA');
if ($xml->get_LastMethodSuccess() == false) {
    print 'Failed to find DA element' . "\n";
    exit;
}

//  We need to get the "flattened" DA XML where:
//    - No whitespace between elements.
//    - The 5 pre-defined entities are converted.
//    - The text is encoded in the ISO-8859-1 character set (Latin-1), 
$sbFlattened = new CkStringBuilder();
$daXml->put_EmitCompact(true);
$daXml->put_EmitXmlDecl(false);
$daXml->GetXmlSb($sbFlattened);

// Compute the SHA-1 message digest of the iso-8859-1 byte representation, 
// and sign it with our RSA private key, getting the result in base64 format.

$privKey = new CkPrivateKey();
$success = $privKey->LoadAnyFormatFile('qa_data/rsa/rsaPrivKey_pkcs8.pem','');
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

$rsa = new CkRsa();
$rsa->ImportPrivateKeyObj($privKey);

$rsa->put_EncodingMode('base64');
$rsa->put_Charset('iso-8859-1');
$sig = $rsa->signStringENC($sbFlattened->getAsString(),'sha1');

// Add the FRMA signature element to the XML.
$xml->UpdateChildContent('Documento|TED|DD|CAF|FRMA',$sig);
$xml->UpdateAttrAt('Documento|TED|DD|CAF|FRMA',true,'algoritmo','SHA1withRSA');

// See what we have:
$xml->put_EmitCompact(false);
$xml->put_EmitXmlDecl(true);
print $xml->getXml() . "\n";

$xml->SaveXml('qa_data/xml_dsig/sii_cl/test_1.xml');

?>