(Xojo Plugin) 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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// 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

Dim xml As New Chilkat.Xml

// 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>

Dim success As Boolean
success = xml.LoadXmlFile("qa_data/xml_dsig/sii_cl/test_0.xml")
If (success = False) Then
    System.DebugLog("Failed to load initial XML file.")
    Return
End If

// Get a reference to the "DA" element
Dim daXml As Chilkat.Xml
daXml = xml.FindChild("Documento|TED|DD|CAF|DA")
If (xml.LastMethodSuccess = False) Then
    System.DebugLog("Failed to find DA element")
    Return
End If

//  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), 
Dim sbFlattened As New Chilkat.StringBuilder
daXml.EmitCompact = True
daXml.EmitXmlDecl = False
success = 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.

Dim privKey As New Chilkat.PrivateKey
success = privKey.LoadAnyFormatFile("qa_data/rsa/rsaPrivKey_pkcs8.pem","")
If (success = False) Then
    System.DebugLog(privKey.LastErrorText)
    Return
End If

Dim rsa As New Chilkat.Rsa
success = rsa.ImportPrivateKeyObj(privKey)

rsa.EncodingMode = "base64"
rsa.Charset = "iso-8859-1"
Dim sig As String
sig = rsa.SignStringENC(sbFlattened.GetAsString(),"sha1")

// Add the FRMA signature element to the XML.
xml.UpdateChildContent "Documento|TED|DD|CAF|FRMA",sig
success = xml.UpdateAttrAt("Documento|TED|DD|CAF|FRMA",True,"algoritmo","SHA1withRSA")

// See what we have:
xml.EmitCompact = False
xml.EmitXmlDecl = True
System.DebugLog(xml.GetXml())

success = xml.SaveXml("qa_data/xml_dsig/sii_cl/test_1.xml")