Mastermind

Guess the secret 4-digit code in as few steps as you can!
You might know this game from your childhood as it is a digital version of the classic Mastermind board game.
The game is completely free and does not interrupt the gameplay with advertisements.

You can read the rules of the original board game in several languages here:
http://en.wikipedia.org/wiki/Mastermind_(board_game)
Note: In this version, black means "right color, wrong place" and white means "right color, right place".