When Apple launched the iPhone 5S equipped with a fingerprint sensor - the Touch ID, it guaranteed the public that their information is safe inside a "secure enclave" within the A7 chip of the device. Now, the company has explained further, via a new patent filed by the with the U.S. Patent & Trademark Office made public on November 21, how the handset handles and secures the user's data.
The patent reported first by Patently Apple outlines the procedure used by the handset to scan a finger, match the data, and grant access to the user.
"Apple's invention includes a process of collapsing the full maps into a sort of checksum, hash function, or histogram. For example, each encrypted ridge map template can have some lower resolution pattern computed and associated with the ridge map. One exemplary pattern could be a histogram of, e.g., the most common angles (e.g., a 2 dimensional (2D) array of common angles)," said Patently Apple.
"The exemplary pattern could include in each slot an average value over a respective vector of the map. The exemplary pattern could include in each slot a sum of the values over a respective vector of the map. The exemplary pattern could include the smallest or largest value within a respective vector of the map, or could be a difference between a largest and a smallest value within the respective vector of the map," it added.
The Touch ID system of the iPhone 5s is basically a one-way street. When it scans a fingerprint, it converts that information into an encrypted data and stores it in the "secure enclave" of its chip. This information can only be used by the system to match newly scanned fingerprints to countercheck and unlock the system for its rightful user. The data stored in the A7 chip cannot be tapped or access by anybody in any way.
In another patent published on November 21, Apple detailed the parts used for the fingerprint sensor of its new handset. The hardware information revealed how the Touch ID sensor can be covered by an opaque lens using an ink assembly.
Both patents were filed during the first quarter of the year. They have not been granted as of reporting.