It can crack your smartphone password in seconds, rip personal data from call and messaging apps, and peruse your contact book.

The Chinese-made XDH-CF-5600 scanner — or "mobile phone sleuth," as sales staff described it when touting its claimed features — was one of hundreds of surveillance gadgets on display at a recent police equipment fair in Beijing.

The China International Exhibition on Police Equipment is something of a one-stop shop for China's police forces looking to arm up with the latest in "black tech" — a term widely used to refer to cutting-edge surveillance gadgets.