Perl

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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Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

my $mime = Chilkat2::Mime->new;
my $success = $mime->LoadMimeFile('qa_data/signed.eml');
if (!$success) {
    print $mime->LastErrorText, "\n";
    exit;
}

# 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) {
    print $mime->LastErrorText, "\n";
    exit;
}

my $n = $mime->NumSignerCerts;
for my $i (0 .. $n - 1) {
    if ($mime->HasSignatureSigningTime($i)) {
        print 'Signer ', $i, " included a signing time.\n";
    } else {
        print 'Signer ', $i, " did not include a signing time.\n";
    }
}