PHP ActiveX

Specify a Certificate for Encrypted Email

Demonstrates the Chilkat Email.AddEncryptCert method, which explicitly specifies a certificate to use when sending encrypted email. Call it once per recipient certificate; ClearEncryptCerts clears the list. This example loads a recipient certificate, registers it, and enables encrypted sending.

Background: When encrypting to multiple people, each recipient needs to be able to decrypt with their own private key. S/MIME handles this by encrypting the message's one-time content key separately under each recipient's public certificate and including all of those wrapped keys in the message. AddEncryptCert is how you build that recipient list — one call per certificate — giving explicit control over exactly whose certificates are used rather than relying on automatic lookup.

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<?php

$success = 0;

//  Demonstrates the AddEncryptCert method, which explicitly specifies a certificate for
//  sending encrypted email.  Call it once per recipient certificate.  Use ClearEncryptCerts
//  to clear the list.

$email = new COM("Chilkat.Email");
$email->Subject = 'Encrypted email';
$email->Body = 'Encrypted to the specified recipient certificate(s).';
$email->From = 'alice@example.com';
$email->AddTo('Bob','bob@example.com');

//  Load a recipient certificate (public key) and add it to the encryption cert list.
$cert = new COM("Chilkat.Cert");
$success = $cert->LoadFromFile('qa_data/certs/recipient.cer');
if ($success == 0) {
    print $cert->LastErrorText . "\n";
    exit;
}

$success = $email->AddEncryptCert($cert);
if ($success == 0) {
    print $email->LastErrorText . "\n";
    exit;
}

//  Request encrypted sending.
$email->SendEncrypted = 1;

print 'Added the recipient's encryption certificate.' . "\n";

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

?>