Dart

Save a Private Key as an Encrypted PKCS #8 DER File

Demonstrates the Chilkat PrivateKey.SavePkcs8EncryptedFile method, which saves the key as password-protected PKCS #8 DER. The first argument is the password and the second is the destination path. The cipher is selected by Pkcs8EncryptAlg.

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: This is the recommended way to persist a key to disk: the binary .der is encrypted under a passphrase, so a stolen file is useless without it. Reach for it whenever a key is stored or shipped. Choose the encryption cipher with Pkcs8EncryptAlg and source the password securely.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Load a private key to export.
  final privKey = CkPrivateKey();
  try {
    privKey.loadPemFile('qa_data/private.pem');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // The key password is not hard-coded in a real application; obtain it from an interactive
  // prompt, environment variable, or a secrets vault.
  final password = 'myKeyPassword';

  // Save as password-protected PKCS #8 DER.  The 1st argument is the password and the 2nd is the
  // destination path.  The cipher is selected by the Pkcs8EncryptAlg property.
  try {
    privKey.savePkcs8EncryptedFile(password, 'qa_output/private_pkcs8_enc.der');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Saved (encrypted).');
}