PowerShell

Get an S/MIME Signing Time

Demonstrates the Chilkat Mime.GetSignatureSigningTimeStr method, which returns the CMS signingTime attribute for the signer at a zero-based index, as an RFC 822-style date string in GMT. The only argument is the signer index.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: This is the timestamp the signer asserted at signing — useful for "when was this signed" audit trails and for evaluating whether the signing certificate was valid at that moment. Because it is a signed attribute, it is tamper-evident. Guard the call with HasSignatureSigningTime, since the attribute is optional. Note it is the signer's claim, not a trusted third-party timestamp.

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

$success = $false

$mime = New-Object Chilkat.Mime
$success = $mime.LoadMimeFile("qa_data/signed.eml")
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

#  After verifying, get the CMS signingTime for each signer that has one, as an RFC 822 date string
#  in GMT.  The only argument is the zero-based signer index.
$success = $mime.Verify()
if ($success -ne $true) {
    $($mime.LastErrorText)
    exit
}

$n = $mime.NumSignerCerts

for ($i = 0; $i -le $n - 1; $i++) {
    #  Only signers that included a signing time have one to retrieve.
    if ($mime.HasSignatureSigningTime($i)) {
        $signingTime = $mime.GetSignatureSigningTimeStr($i)
        if ($mime.LastMethodSuccess -eq $false) {
            $($mime.LastErrorText)
            exit
        }

        $("Signer " + $i + " signing time: " + $signingTime)
    }

}