SSH Authenticate using a Smart Card Private Key

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Demonstrates using a private key stored on an HSM (smart card or token) for SSH public-key authentication. A JSON template locates the private and public key objects by class, key type, and label, and the returned handles are bound to an SshKey object.

import 'package:chilkat/chilkat.dart';

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

  // Demonstrates using a private key stored on an HSM (smart card or token) for SSH public-key
  // authentication.  Public-key authentication means the client uses the private key, while the
  // corresponding public key is installed on the server under the SSH account.
  // 
  // Note: Chilkat's PKCS#11 implementation runs on Windows, Linux, macOS, and other supported
  // operating systems.

  final pkcs11 = CkPkcs11();

  // Use the PKCS#11 driver (.dll, .so, or .dylib) for your particular HSM.
  pkcs11.sharedLibPath = 'C:/Program Files (x86)/Gemalto/IDGo 800 PKCS#11/IDPrimePKCS11.dll';

  // The HSM PIN should come from a secure source rather than being hard-coded.
  final pin = '0000';

  // Normal user = 1
  final userType = 1;

  try {
    pkcs11.quickSession(userType, pin);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Provide a template describing the PKCS#11 object to find: an RSA private key labeled
  // "MySshKey".  For how such a key is originally imported, see
  // PKCS11 Import SSH Key
  final jsonTemplate = CkJsonObject();
  jsonTemplate.updateString('class', 'private_key');
  jsonTemplate.updateString('key_type', 'rsa');
  jsonTemplate.updateString('label', 'MySshKey');

  final privKeyHandle = pkcs11.findObject(jsonTemplate);
  if (privKeyHandle == 0) {
    print(pkcs11.lastErrorText);
    return;
  }

  // The handle is only valid for the duration of this PKCS#11 session.  To use the key in a
  // later session, find it again.
  print('private key handle: $privKeyHandle');

  // Find the corresponding public key by changing the class in the same template.
  jsonTemplate.updateString('class', 'public_key');

  final pubKeyHandle = pkcs11.findObject(jsonTemplate);
  if (pubKeyHandle == 0) {
    print(pkcs11.lastErrorText);
    return;
  }

  print('public key handle: $pubKeyHandle');

  // Create an empty SSH key object and tell it to use the PKCS#11 handles, indicating the key type.
  final sshKey = CkSshKey();
  try {
    sshKey.usePkcs11(pkcs11, privKeyHandle, pubKeyHandle, 'rsa');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final ssh = CkSsh();

  final port = 22;
  try {
    ssh.connect('ssh.example.com', port);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Authentication uses the existing PKCS#11 session.  The signing happens on the smart card --
  // the private key never leaves the device.
  try {
    ssh.authenticatePk('mySshLogin', sshKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Public-key authentication successful.');

  // ... use the authenticated SSH session ...

  ssh.disconnect();

  pkcs11.logout();
  pkcs11.closeSession();
}