Xbase++

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.

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LOCAL nSuccess
LOCAL oMime
LOCAL n
LOCAL i

nSuccess := 0

oMime := CreateObject("Chilkat.Mime")
nSuccess := oMime:LoadMimeFile("qa_data/signed.eml")
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
ENDIF

//  After verifying, check whether each signer included a CMS signingTime signed attribute.  The
//  only argument is the zero-based signer index.
nSuccess := oMime:Verify()
IF (nSuccess != 1)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
ENDIF

n := oMime:NumSignerCerts

FOR i := 0 TO n - 1
    IF (oMime:HasSignatureSigningTime(i))
        ? "Signer " + Str(i) + " included a signing time."
    ELSE
        ? "Signer " + Str(i) + " did not include a signing time."
    ENDIF

NEXT

oMime:destroy()