DataFlex

Supply a Fallback Certificate for S/MIME Verification

Demonstrates the Chilkat Mime.SetVerifyCert method, which supplies a signer-certificate fallback for subsequent signature verification. The only argument is the Cert.

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

Background: Most signed messages embed the signer's certificate, so Verify can find it automatically. But some signatures omit it to save space, expecting the recipient to already have it. This method provides that certificate as a fallback so verification can proceed — the S/MIME equivalent of already knowing the sender's public key out of band.

Chilkat DataFlex Downloads

Download Chilkat for DataFlex

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoMime
    Variant vCert
    Handle hoCert
    String sTemp1

    Move False To iSuccess

    Get Create (RefClass(cComChilkatMime)) To hoMime
    If (Not(IsComObjectCreated(hoMime))) Begin
        Send CreateComObject of hoMime
    End
    Get ComLoadMimeFile Of hoMime "qa_data/signed.eml" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoMime To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Supply a signer-certificate fallback for verification.  This is useful when the signature does
    //  not embed the signer certificate and Chilkat cannot otherwise locate it.
    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End
    Get ComLoadFromFile Of hoCert "qa_data/signer.cer" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get pvComObject of hoCert to vCert
    Get ComSetVerifyCert Of hoMime vCert To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoMime To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Now verify using the supplied certificate.
    Get ComVerify Of hoMime To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoMime To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Signature verified using the supplied certificate."


End_Procedure