C++

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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C++

#include <CkMime.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkMime mime;
    success = mime.LoadMimeFile("qa_data/signed.eml");
    if (success == false) {
        std::cout << mime.lastErrorText() << "\r\n";
        return;
    }

    //  After verifying, check whether each signer included a CMS signingTime signed attribute.  The
    //  only argument is the zero-based signer index.
    success = mime.Verify();
    if (success != true) {
        std::cout << mime.lastErrorText() << "\r\n";
        return;
    }

    int n = mime.get_NumSignerCerts();
    int i;
    for (i = 0; i <= n - 1; i++) {
        if (mime.HasSignatureSigningTime(i)) {
            std::cout << "Signer " << i << " included a signing time." << "\r\n";
        }
        else {
            std::cout << "Signer " << i << " did not include a signing time." << "\r\n";
        }

    }
    }