Which is usually a four digit code, since you have to type it in so often? That's about 10,000 combinations. It's trivial to go through all the combinations. Ev

Which is usually a four digit code, since you have to type it in so often? That's about 10,000 combinations. It's trivial to go through all the combinations. Even if it took a second per combination, it'd be cracked under three hours. A more sensible way to encrypt a device is to use a separate long code that only has to be typed in at boot. Using a screen lock as an encryption key is just not effective.