Example of how to prompt for password in dart console using streams. Not exactly secure since echo is not disabled. Taken from the dart-gde discovery project

prompt_password.dart

/**
 * $ cat /Applications/dart/dart-sdk/version 
 * 0.4.1.0_r19425
 */
import "dart:io";
import "dart:uri";
import "dart:async";

Future<String> promptPassword() {
  var completer = new Completer<String>();
  StreamSubscription stdinSubscription;

  stdout.addString("enter password: ");

  readLine(String line) {
    stdout.addString("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
    stdinSubscription.cancel();
    completer.complete(line);
  };

  stdinSubscription = stdin
  .transform(new StringDecoder())
  .transform(new LineTransformer())
  .listen(readLine);

  return completer.future;
}

void main() {
  promptPassword().then((password)=>print("password = $password"));
}