Simson L. Garfinkel, writing in Technology Review, notes that the DOJ believes that iPhone encryption is “too secure.”

“I can tell you from the Department of Justice perspective, if that drive is encrypted, you’re done,” said Ovie Carroll, director at the Justice Dept.’s Computer Crime and Intellectual Property Section, during his address earlier this month.

“When conducting criminal investigations, if you pull the power on a drive that is whole-disk encrypted you have lost any chance of recovering that data.”

To reach such a high security level it is important that the user implement a numerical PIN that must be entered to access the device, and that the PIN be longer than four numbers.

Read the entire article for all the details. I can say that I have increased the length of my PIN already.