Xojo Plugin

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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Dim success As Boolean
success = False

Dim mime As New Chilkat.Mime
success = mime.LoadMimeFile("qa_data/signed.eml")
If (success = False) Then
    System.DebugLog(mime.LastErrorText)
    Return
End If

//  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 <> True) Then
    System.DebugLog(mime.LastErrorText)
    Return
End If

Dim n As Int32
n = mime.NumSignerCerts
Dim i As Int32
For i = 0 To n - 1
    //  Only signers that included a signing time have one to retrieve.
    If (mime.HasSignatureSigningTime(i)) Then
        Dim signingTime As String
        signingTime = mime.GetSignatureSigningTimeStr(i)
        If (mime.LastMethodSuccess = False) Then
            System.DebugLog(mime.LastErrorText)
            Return
        End If

        System.DebugLog("Signer " + Str(i) + " signing time: " + signingTime)
    End If

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