I'm trying to mask the characters entered in the console with '*' but it is just repeatedly printin asterisks, anyone know what i can do?

Question

using System;

class MainClass {
  public static void Main (string[] args) {
    Console.Write("password: ");
    string password = null;
    while (true){
      var key = Console.ReadKey(true);
      Console.Write("*");
      password += key.KeyChar;
      if (key.Key == ConsoleKey.Enter)
      break;
    }
  }
}

while (true){

I'm trying to get it to read the key entered and then print an '*' but it is just endlessly printing *'s

var key = Console.ReadKey(true);
Console.Write("*");