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Check for an S/MIME Signing Time

Demonstrates the Chilkat Mime.HasSignatureSigningTime method, which returns whether the signer at a zero-based index included a CMS signingTime signed attribute. The only argument is the signer index; use NumSignerCerts for the count.

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: A signing time records when the signer claims to have signed, which matters for auditing and for validating a certificate that has since expired. It is an optional signed attribute, so not every signature has one — this predicate lets you check before calling GetSignatureSigningTimeStr, avoiding an error for signers that omitted it. Being a signed attribute, it is covered by the signature and cannot be altered undetected.

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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, check whether each signer included a CMS signingTime signed attribute.  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; $i++) {
    if ($mime.HasSignatureSigningTime($i)) {
        $("Signer " + $i + " included a signing time.")
    }
    else {
        $("Signer " + $i + " did not include a signing time.")
    }

}