(PHP Extension) Send Encrypted Email with a Selected Algorithm (AES, 3DES, etc.)

Sends an encrypted email using the recipient's digital certificate from a .cer file, and chooses 3DES for the encryption algorithm. (It is also possible to send AES encrypted email w/ 128-bit, 192-bit, or 256-bit encryption simply by setting the Pkcs7CryptAlg and Pkcs7KeyLength properties.)

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// The mailman object is used for sending and receiving email.
$mailman = new CkMailMan();

// Set the SMTP server.
$mailman->put_SmtpHost('smtp.mymailserver.com');

// Load the .cer file into a certificate object.
// When sending S/MIME encrypted email, it is the recipient's
// certificate that is used for encryption.  Only the public key
// is needed to encrypt.  The recipient is the only
// one possessing the private key, and therefore is the only
// one able to decrypt.
$cert = new CkCert();
$success = $cert->LoadFromFile('cknotes.cer');
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// Create a new email object
$email = new CkEmail();

$email->put_Subject('This email is encrypted');
$email->put_Body('This is a digitally encrypted mail');
$email->put_From('Chilkat Support <support@chilkatsoft.com>');
$success = $email->AddTo('Chilkat Blog','admin@cknotes.com');

// Indicate that the email is to be sent encrypted.
$email->put_SendEncrypted(true);

// Specify the certificate to be used for encryption.
$success = $email->SetEncryptCert($cert);

// If desired, specify the encryption algorithm to be used.
// The Pkcs7CryptAlg property can be set to "aes", "des", "3des", or "rc2"
$email->put_Pkcs7CryptAlg('3des');

// If desired, set the key length (in bits) for the encryption algorithm:
// The possible values allowed depend on the Pkcs7CryptAlg property. 
// For "aes", the key length may be 128, 192, or 256. 
// For "3des" the key length must be 192. 
// For "des" the key length must be 40. 
// For "rc2" the key length can be 40, 56, 64, or 128.
$email->put_Pkcs7KeyLength(192);

$success = $mailman->SendEmail($email);
if ($success != true) {
    print $mailman->lastErrorText() . "\n";
}
else {
    print 'Mail Sent!' . "\n";
}


?>