PHP ActiveX

Get the Signer Certificate of a Signed Email

Demonstrates the Chilkat Email.LastSignerCert method, which copies the certificate for the signer at a given zero-based index into a Cert object. Most signed emails have one signer (index 0), but a message can have more than one. This example loads a signed email and reads the first signer's common name.

Background: Confirming that a signature is valid (see SignaturesValid) tells you the content wasn't altered, but not who signed it. LastSignerCert gives you the signer's certificate as an object so you can examine its subject and issuer and evaluate trust — an essential step before relying on a signature to establish the sender's identity.

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<?php

$success = 0;

//  Demonstrates the LastSignerCert method, which copies the certificate for the signer at
//  the given zero-based index into a Cert object.  Most signed emails have one signer
//  (index 0), but a message can have more than one.

$email = new COM("Chilkat.Email");

$success = $email->LoadEml('qa_data/eml/signed.eml');
if ($success == 0) {
    print $email->LastErrorText . "\n";
    exit;
}

if ($email->ReceivedSigned == 1) {
    //  Get the certificate of the first signer (index 0).
    $cert = new COM("Chilkat.Cert");
    $success = $email->LastSignerCert(0,$cert);
    if ($success == 1) {
        print 'Signer certificate (CN): ' . $cert->SubjectCN . "\n";
    }

}

//  Note: The path "qa_data/..." is a relative local filesystem path,
//  relative to the current working directory of the running application.

?>