The iPhone 5S includes major internal upgrades but maintains almost the same external design as its predecessor, the iPhone 5, although the 5S received a new white/gold color scheme in addition to white/silver and space gray/black. A redesigned home button with Touch ID, a fingerprint recognition system which can be used to unlock the phone and authenticate App Store and iTunes Storepurchases, was introduced. The camera was updated with a larger aperture and a dual-LED flash optimized for different color temperatures. The 5S also introduced the A7 64-bit dual-core processor, the first 64-bit processor to be used on a smartphone, accompanied by the M7 "motion co-processor".