Dart

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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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // 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.

  final email = CkEmail();
  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.
  final cert = CkCert();
  try {
    cert.loadFromFile('qa_data/certs/recipient.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    email.addEncryptCert(cert);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Request encrypted sending.
  email.sendEncrypted = true;

  print('Added the recipient\'s encryption certificate.');

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