(PowerShell) 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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Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

# 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-Object 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>

$success = $xml.LoadXmlFile("qa_data/xml_dsig/sii_cl/test_0.xml")
if ($success -eq $false) {
    $("Failed to load initial XML file.")
    exit
}

# Get a reference to the "DA" element
$daXml = $xml.FindChild("Documento|TED|DD|CAF|DA")
if ($xml.LastMethodSuccess -eq $false) {
    $("Failed to find DA element")
    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-Object Chilkat.StringBuilder
$daXml.EmitCompact = $true
$daXml.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-Object Chilkat.PrivateKey
$success = $privKey.LoadAnyFormatFile("qa_data/rsa/rsaPrivKey_pkcs8.pem","")
if ($success -eq $false) {
    $($privKey.LastErrorText)
    exit
}

$rsa = New-Object Chilkat.Rsa
$rsa.ImportPrivateKeyObj($privKey)

$rsa.EncodingMode = "base64"
$rsa.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.EmitCompact = $false
$xml.EmitXmlDecl = $true
$($xml.GetXml())

$xml.SaveXml("qa_data/xml_dsig/sii_cl/test_1.xml")