Perl

Get the S/MIME Signer's Certificate

Demonstrates the Chilkat Mime.LastSignerCert method, which loads the signer certificate at a zero-based index from the most recent successful verification (or security-unwrapping) into a Cert. The first argument is the signer index and the second is the receiving Cert.

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: Verifying tells you the signature is mathematically valid, but you usually also need to know who signed — the subject, the issuer, the validity dates — to decide whether to trust it. This retrieves each signer's certificate after verification so your code can inspect and apply its own trust rules. A message can have multiple signers, so iterate from 0 to NumSignerCerts - 1.

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Perl

use chilkat();

$success = 0;

$mime = chilkat::CkMime->new();
$success = $mime->LoadMimeFile("qa_data/signed.eml");
if ($success == 0) {
    print $mime->lastErrorText() . "\r\n";
    exit;
}

#  After a successful verification, load each signer's certificate to inspect it.  The 1st argument
#  is the zero-based signer index and the 2nd is a Cert object that receives the certificate.
$success = $mime->Verify();
if ($success != 1) {
    print $mime->lastErrorText() . "\r\n";
    exit;
}

$n = $mime->get_NumSignerCerts();
$cert = chilkat::CkCert->new();

for ($i = 0; $i <= $n - 1; $i++) {
    $success = $mime->LastSignerCert($i,$cert);
    if ($success == 0) {
        print $mime->lastErrorText() . "\r\n";
        exit;
    }

    print "Signer " . $i . ": " . $cert->subjectCN() . " (issued by " . $cert->issuerCN() . ")" . "\r\n";
}