(Visual Basic 6.0) IMAP Download and Verify Signed MIME

Downloads the original MIME of a digitally signed email and saves the .p7s signature along with other MIME parts. It then imports the email into a Chilkat email object to unwrap the S/MIME and verify the signature, and subsequently saves the attachments if they haven't been saved already.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Dim success As Long
success = 0

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

Dim imap As New ChilkatImap

' Connect to an IMAP server.
' Use TLS
imap.Ssl = 1
imap.Port = 993
success = imap.Connect("imap.example.com")
If (success = 0) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

success = imap.Login("myLogin","myPassword")
If (success = 0) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
If (success = 0) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Download the 1st email (as MIME) in the Inbox by sequence number.
Dim sbMime As New ChilkatStringBuilder
success = imap.FetchSingleAsMimeSb(1,0,sbMime)
If (success = 0) Then
    Debug.Print imap.LastErrorText
    Exit Sub
End If

' Load it into a MIME object and check to see if it is signed
Dim mime As New ChilkatMime
success = mime.LoadMimeSb(sbMime)
Dim alreadySavedParts As Long
alreadySavedParts = 0
If (mime.ContainsSignedParts() = 1) Then

    ' This will save the .p7s and other parts...
    Dim st As New ChilkatStringTable
    success = mime.PartsToFiles("c:/temp/qa_output",st)
    If (success = 1) Then
        Dim numFiles As Long
        numFiles = st.Count
        Dim i As Long
        i = 0
        Do While i < numFiles
            Debug.Print "Created: " & st.StringAt(i)
            i = i + 1
        Loop
        alreadySavedParts = 1
    End If

End If

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

If (email.ReceivedSigned = 1) Then

    Debug.Print "This email was signed."

    ' Check to see if the signatures were verified.
    If (email.SignaturesValid = 1) Then
        Debug.Print "Digital signature(s) verified."

        Debug.Print "Signer: " & email.SignedBy

        ' The certificate used for signing may be obtained
        ' by calling email.GetSignedByCert.
        Dim cert As New ChilkatCert
        success = email.LastSignerCert(i,cert)
        If (success = 0) Then
            Debug.Print "Failed to get signing certificate object."
        Else
            Debug.Print "Signing cert: " & cert.SubjectCN
        End If

    End If

Else
    Debug.Print "Digital signature verification failed."
End If

If (alreadySavedParts <> 1) Then
    success = email.SaveAllAttachments("c:/temp/qa_output")
End If