Hackers have posted online the unique ID numbers for more than 1 million Apple devices like iPhones and iPads, saying they stole the data from an FBI laptop, a claim the bureau denies.

The ID numbers could be used to impersonate the devices, allowing hackers to access personal information about their owners from apps they have installed, according to Alex Horan, product manager at Boston-based CORE Security.

The ID numbers are unique to each device and cannot be changed, said Mr. Horan, so they are generally accepted to provide a failsafe way to identify a particular device and its user, “Like DNA for a phone.”

The hackers said the million-and-one IDs they published — many of which have been verified as genuine by security analysts — came from a trove of more than 12 million IDs and other personal information about the phones’ users that they stole from an FBI laptop.

READ MORE: WASHINGTON TIMES