Xojo Plugin

Check if a MIME Entity is Signed (S/MIME)

Demonstrates the Chilkat Mime.IsSigned method, which returns whether the entity is a complete CMS/PKCS #7 signed S/MIME wrapper, including detached multipart/signed and opaque forms. It takes no arguments.

Note: The file path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own file.

Background: Before verifying a signature you need to know one is present, and this is the check. A signed S/MIME message comes in two shapes — detached (multipart/signed, signature alongside the content) and opaque (application/pkcs7-mime, content wrapped inside the signature) — and this recognizes both. Follow a true result with Verify.

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Xojo Plugin

Dim success As Boolean
success = False

//  Demonstrates the Mime.IsSigned method, which returns whether the entity is a complete CMS/PKCS #7 signed S/MIME wrapper.  It takes no arguments.

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

If (mime.IsSigned()) Then
    System.DebugLog("This is a signed S/MIME message.")
Else
    System.DebugLog("This is not a signed S/MIME message.")
End If