(VB.NET) IMAP Download and Verify Signed MIME

Downloads the unmodified MIME of a digitally signed email, saves the .p7s signature (and other MIME parts), then loads the email into a Chilkat email object (which unwraps the S/MIME and verifies the signature) and then saves attachments (if the MIME parts were not already saved).

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

Dim imap As New Chilkat.Imap

' Connect to an IMAP server.
' Use TLS
imap.Ssl = True
imap.Port = 993
Dim success As Boolean = imap.Connect("imap.someMailServer.com")
If (success <> True) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


success = imap.Login("myLogin","myPassword")
If (success <> True) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


' Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
If (success <> True) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


' Download the 1st email (as MIME) in the Inbox by sequence number.
Dim sbMime As New Chilkat.StringBuilder
success = imap.FetchSingleAsMimeSb(1,False,sbMime)
If (success <> True) Then
    Debug.WriteLine(imap.LastErrorText)
    Exit Sub
End If


' Load it into a MIME object and check to see if it is signed
Dim mime As New Chilkat.Mime
mime.LoadMimeSb(sbMime)
Dim alreadySavedParts As Boolean = False
If (mime.ContainsSignedParts() = True) Then

    ' This will save the .p7s and other parts...
    Dim sa As Chilkat.StringArray = mime.ExtractPartsToFiles("qa_output")
    If (mime.LastMethodSuccess = True) Then
        Dim numFiles As Integer = sa.Count
        Dim i As Integer = 0
        While i < numFiles
            Debug.WriteLine("Created: " & sa.GetString(i))
            i = i + 1
        End While

        alreadySavedParts = True
    End If

End If


' Load the MIME into an Email object.  This unwraps the security layers and verifies signatures.
Dim email As New Chilkat.Email
email.SetFromMimeSb(sbMime)

If (email.ReceivedSigned = True) Then

    Debug.WriteLine("This email was signed.")

    ' Check to see if the signatures were verified.
    If (email.SignaturesValid = True) Then
        Debug.WriteLine("Digital signature(s) verified.")

        Debug.WriteLine("Signer: " & email.SignedBy)

        ' The certificate used for signing may be obtained
        ' by calling email.GetSignedByCert.
        Dim cert As Chilkat.Cert = email.GetSignedByCert()
        If (email.LastMethodSuccess <> True) Then
            Debug.WriteLine("Failed to get signing certificate object.")
        Else
            Debug.WriteLine("Signing cert: " & cert.SubjectCN)

        End If

    End If


Else
    Debug.WriteLine("Digital signature verification failed.")
End If


If (alreadySavedParts <> True) Then
    email.SaveAllAttachments("qa_output")
End If