Touch IDis Apple’s first attempt at biometric authentication with the iPhone. First introduced with the iPhone 5S home button, it was later implemented on iPads and the Mac Magic Keyboard. It is still used as a special form of biometrics on Macs, select iPad models, and the iPhone SE.

Touch ID has changed the way users authenticate on their devices. Before iPhone 5S, most users used their smartphones without any passcode or preferred 4-digit pins for passcode.

How Does Touch ID Work?

Touch ID works through sensors embedded in the finger pod on the home button on your device. When you touch the compartment with your finger, the steel ring sends a message to the sensor and the biometric details are read and recorded on your device.

Since each person’s fingerprint is different, the fingerprint that will be recognized by Touch ID after registering it on the device is unique to the person. Thanks to this fingerprint registration, settings such as purchasing and app locking can be enabled.

Is Touch ID Secure?

There is no need to worry about your personal information because Apple has confirmed that they do not have access to this data. Touch ID is recommended by security experts as it will provide an additional level of security to your devices and data.

What are the Touch ID Features?

Apple allows users to create fingerprint scans of up to five fingers per device. Touch ID relies on the same scanning technology and Secure Enclave data storage on every Apple device, regardless of its shape or location.

Fingerprint Sensor

The fingerprint reader used in Apple products uses a sapphire crystal surface surrounded by a steel ring. The glass protects the components used to recognize fingerprints underneath.

When a finger is detected, a high-resolution image is captured using capacitive touch. This image is converted to a numerical value and encrypted before being passed to the Secure Enclave.

The final value produced by the sensor is compared to a value stored in the Secure Enclave. If it matches one of the stored values, the fingerprint is recognized and the device is unlocked.

Secure Enclave

Apple’s T2 Security chip is a 64-bit ARMv8 chipset that runs a separate operating system called bridgeOS 2.0. It handles the entire boot process, all encryption, audio processing, camera control, and System Management Controller features using a custom AES hardware engine.

The Secure Enclave and the sensor have a shared key that is used to create a session key that encrypts and authenticates the data. All data collected by the sensor is sent to the T2 Security chip using a dedicated serial peripheral interface bus. The T2 chip then transmits this data to the Secure Enclave for processing.

Secure Enclave is a coprocessor (or hardware-based key manager) physically located within the application processor package. It operates isolated from the system and communicates with the main chip using an interrupt-based “mailbox”. Because it is isolated and self-supporting, it maintains its integrity even if the operating system is compromised.

Secure Enclave converts the data provided by the sensor into mathematical representations. Since the Secure Enclave’s 4MB of storage is used only for 256-bit elliptic curve private keys, these numbers are encrypted and stored in the file system.

Secure Enclave stores the class key and processes all wrapped file keys, which are never exposed to the host processor. The file system metadata key is encrypted using the Secure Enclave’s Hardware UID (Unique Identifier) ​​key on devices using the Apple File System. The chipset’s firmware encrypts all keys stored in the Secure Enclave.

Using Biometrics

Touch ID not only unlocks a device but is also used for more apps.

For example, it is integrated into Apple’s operating systems for secure access to information and payments. Banking apps, secure messaging apps, and others have widely implemented this feature.

Models using Touch ID

Models with 1st Generation Touch ID

• iPhone 5S
• iPhone SE
• iPhone 6
• iPhone 6 Plus
• iPad Air 2
• ipad mini 3
• iPad mini 4
• iPad Pro 12.9
• iPad Pro 9.7

Models with 2nd Generation Touch ID

• iPhone 6S
• iPhone 6S Plus
• iPhone 7
• iPhone 7 Plus
• MacBook Pro