Xojo Plugin

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.

Chilkat Xojo Plugin Downloads

Download Chilkat for Xojo Plugin

Xojo Plugin

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, check whether each signer included a CMS signingTime signed attribute.  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
    If (mime.HasSignatureSigningTime(i)) Then
        System.DebugLog("Signer " + Str(i) + " included a signing time.")
    Else
        System.DebugLog("Signer " + Str(i) + " did not include a signing time.")
    End If

Next