Get an S/MIME Signing Time

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Demonstrates the Chilkat Mime.GetSignatureSigningTimeStr method, which returns the CMS signingTime attribute for the signer at a zero-based index, as an RFC 822-style date string in GMT. The only argument is the signer index.

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: This is the timestamp the signer asserted at signing — useful for "when was this signed" audit trails and for evaluating whether the signing certificate was valid at that moment. Because it is a signed attribute, it is tamper-evident. Guard the call with HasSignatureSigningTime, since the attribute is optional. Note it is the signer's claim, not a trusted third-party timestamp.

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#include <C_CkMime.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkMime mime;
    int n;
    int i;
    const char *signingTime;

    success = FALSE;

    mime = CkMime_Create();
    success = CkMime_LoadMimeFile(mime,"qa_data/signed.eml");
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        return;
    }

    //  After verifying, get the CMS signingTime for each signer that has one, as an RFC 822 date string
    //  in GMT.  The only argument is the zero-based signer index.
    success = CkMime_Verify(mime);
    if (success != TRUE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        return;
    }

    n = CkMime_getNumSignerCerts(mime);

    for (i = 0; i <= n - 1; i++) {
        //  Only signers that included a signing time have one to retrieve.
        if (CkMime_HasSignatureSigningTime(mime,i)) {
            signingTime = CkMime_getSignatureSigningTimeStr(mime,i);
            if (CkMime_getLastMethodSuccess(mime) == FALSE) {
                printf("%s\n",CkMime_lastErrorText(mime));
                CkMime_Dispose(mime);
                return;
            }

            printf("Signer %d signing time: %s\n",i,signingTime);
        }

    }



    CkMime_Dispose(mime);

    }