Visual FoxPro

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 lnSuccess
LOCAL loMime
LOCAL n
LOCAL i

lnSuccess = 0

loMime = CreateObject('Chilkat.Mime')
lnSuccess = loMime.LoadMimeFile("qa_data/signed.eml")
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

*  After verifying, check whether each signer included a CMS signingTime signed attribute.  The
*  only argument is the zero-based signer index.
lnSuccess = loMime.Verify()
IF (lnSuccess <> 1) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

n = loMime.NumSignerCerts

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

NEXT

RELEASE loMime