DataFlex

Check if an Email Was Received Digitally Signed

Demonstrates the read-only Chilkat Email.ReceivedSigned property, which is true if the email was originally received carrying one or more digital signatures. Knowing a message was signed is separate from knowing the signature checked out, so this example also reads SignaturesValid to report whether the signed content verified.

Background: A digital signature on an email (S/MIME) provides two things: authenticity (it was really sent by the holder of a particular certificate) and integrity (the content was not altered in transit). The sender signs a hash of the message with their private key; the recipient verifies it with the sender's public certificate. ReceivedSigned simply tells you a signature is present — verifying it is a separate step exposed through SignaturesValid.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoEmail
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  Demonstrates the read-only Email.ReceivedSigned property, which is true if this
    //  email was originally received with a digital signature.  Use SignaturesValid to
    //  determine whether the signed content actually verified.

    Get Create (RefClass(cComChilkatEmail)) To hoEmail
    If (Not(IsComObjectCreated(hoEmail))) Begin
        Send CreateComObject of hoEmail
    End

    Get ComLoadEml Of hoEmail "qa_data/eml/signed.eml" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoEmail To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComReceivedSigned Of hoEmail To bTemp1
    If (bTemp1 = True) Begin
        Showln "This email was received with a digital signature."
        Get ComSignaturesValid Of hoEmail To bTemp1
        If (bTemp1 = True) Begin
            Showln "All signatures are valid."
        End
        Else Begin
            Showln "One or more signatures are NOT valid."
        End

    End
    Else Begin
        Showln "This email was not signed."
    End

    //  Note: Paths such as "qa_data/..." are relative local filesystem paths,
    //  relative to the current working directory of the running application.


End_Procedure