PHP

Get an S/MIME Signing Time

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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<?php

use Chilkat2\Mime;

$mime = new Mime();
try {
    $mime->LoadMimeFile('qa_data/signed.eml');

    // 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.
    $mime->Verify();
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

$n = $mime->NumSignerCerts;
for ($i = 0; $i < $n; $i++) {
    // Only signers that included a signing time have one to retrieve.
    if ($mime->HasSignatureSigningTime($i)) {
        try {
            $signingTime = $mime->GetSignatureSigningTimeStr($i);
        } catch (\Chilkat2\Exception $e) {
            echo $e->getMessage(), "\n";
            exit;
        }

        echo 'Signer ', $i, ' signing time: ', $signingTime, "\n";
    }
}