Get an S/MIME Signing Time

See more MIME Examples

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.

Chilkat C# Downloads

Download Chilkat for C#

bool success = false;

Chilkat.Mime mime = new Chilkat.Mime();
success = mime.LoadMimeFile("qa_data/signed.eml");
if (success == false) {
    Debug.WriteLine(mime.LastErrorText);
    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 = mime.Verify();
if (success != true) {
    Debug.WriteLine(mime.LastErrorText);
    return;
}

int n = mime.NumSignerCerts;
int i;
for (i = 0; i <= n - 1; i++) {
    //  Only signers that included a signing time have one to retrieve.
    if (mime.HasSignatureSigningTime(i)) {
        string signingTime = mime.GetSignatureSigningTimeStr(i);
        if (mime.LastMethodSuccess == false) {
            Debug.WriteLine(mime.LastErrorText);
            return;
        }

        Debug.WriteLine("Signer " + Convert.ToString(i) + " signing time: " + signingTime);
    }

}