(PowerShell) Examine KeyInfo Certificate in XML Signature

This example loads signed XML and gets the signing certificate, assuming the certificate is contained in X509Certificate within the KeyInfo.

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

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

$dsig = New-Object Chilkat.XmlDSig
$sbXml = New-Object Chilkat.StringBuilder

$success = $sbXml.LoadFile("c:/aaworkarea/elias/3/face_f09006808443a699d1b.xml","utf-8")
if ($success -ne $true) {
    $("Failed to load XML file.")
    exit
}

$success = $dsig.LoadSignatureSb($sbXml)
if ($success -ne $true) {
    $($dsig.LastErrorText)
    exit
}

# Get the KeyInfo XML.
$xmlKeyInfo = $dsig.GetKeyInfo()
if ($dsig.LastMethodSuccess -ne $true) {
    $($dsig.LastErrorText)
    exit
}

$($xmlKeyInfo.GetXml())
$("----")

# Assuming the X509Certificate is in the KeyInfo, it will look like this:

#   <ds:KeyInfo Id="...">
#     <ds:KeyValue>
#     ...  
#     <ds:X509Data>
#       <ds:X509Certificate>MIIHAz...</ds:X509Certificate>
#     </ds:X509Data>
#   </ds:KeyInfo>
$certBase64 = $xmlKeyInfo.GetChildContent("*:X509Data|*:X509Certificate")
if ($xmlKeyInfo.LastMethodSuccess -ne $true) {
    $("No X509Certificate found in the KeyInfo.")
    exit
}

# Load a certificate object w/ the base64.
$cert = New-Object Chilkat.Cert
$success = $cert.LoadFromBase64($certBase64)
if ($success -ne $true) {
    $($cert.LastErrorText)
    exit
}

# Examine the cert..
$("SubjectDN: " + $cert.SubjectDN)
$("IssuerDN: " + $cert.IssuerDN)
$("SerialNumber as Decimal: " + $cert.SerialDecimal)