PureBasic

Check for an S/MIME Signing Time

Demonstrates the Chilkat Mime.HasSignatureSigningTime method, which returns whether the signer at a zero-based index included a CMS signingTime signed attribute. The only argument is the signer index; use NumSignerCerts for the count.

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: A signing time records when the signer claims to have signed, which matters for auditing and for validating a certificate that has since expired. It is an optional signed attribute, so not every signature has one — this predicate lets you check before calling GetSignatureSigningTimeStr, avoiding an error for signers that omitted it. Being a signed attribute, it is covered by the signature and cannot be altered undetected.

Chilkat PureBasic Downloads

Download Chilkat for PureBasic

PureBasic

IncludeFile "CkMime.pb"

Procedure ChilkatExample()

    success.i = 0

    mime.i = CkMime::ckCreate()
    If mime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkMime::ckLoadMimeFile(mime,"qa_data/signed.eml")
    If success = 0
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        ProcedureReturn
    EndIf

    ;  After verifying, check whether each signer included a CMS signingTime signed attribute.  The
    ;  only argument is the zero-based signer index.
    success = CkMime::ckVerify(mime)
    If success <> 1
        Debug CkMime::ckLastErrorText(mime)
        CkMime::ckDispose(mime)
        ProcedureReturn
    EndIf

    n.i = CkMime::ckNumSignerCerts(mime)
    i.i
    For i = 0 To n - 1
        If CkMime::ckHasSignatureSigningTime(mime,i)
            Debug "Signer " + Str(i) + " included a signing time."
        Else
            Debug "Signer " + Str(i) + " did not include a signing time."
        EndIf

    Next


    CkMime::ckDispose(mime)


    ProcedureReturn
EndProcedure