Verify and Unwrap PCKS7 Signed MIME

Demonstrates calling the Verify method to verify and unwrap PKCS7 signed MIME. The MIME is restored to the original structure that it would have originally had prior to signing. The Verify method works with both detached signatures, as well as opaque/attached signatures.

Download Chilkat MIME ActiveX

Dim mime As New ChilkatMime

Dim success As Long
success = mime.UnlockComponent("Anything for 30-day trial")
If (success = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  A PKCS7 signature usually embeds both the signing
'  certificate with its public key.  Therefore, it is usually
'  possible to verify a signature without the need to
'  already have the certificate installed.

'  Load the signed MIME from a file...
success = mime.LoadMimeFile("signedMime.txt")
If (success = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  Verify the signed MIME and restore the MIME
'  to the structure/content it had prior to signing.
Dim verified As Long
verified = mime.Verify()
If (verified = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  Examine the MIME after signature verification (i.e. "unwrapping")
Text1.Text = Text1.Text & mime.GetMime() & vbCrLf