Apple T2 - Wikipedia

The main application processor in T2 is a variant of the Apple A10, which is a 64-bit ARMv8.1-A based CPU.[1] It is manufactured by TSMC on their 16 nm process, just as the A10. Analysis of the die reveals a nearly identical CPU macro as the A10 which reveals a four core design for its main application processor, with two large high performance cores, "Hurricane", and two smaller efficiency cores, "Zephyr". Analysis also reveals the same amount of RAM controllers, but a much reduced GPU facility; three blocks, only a quarter the size compared to A10.[1]

The die measures 9.6 mm × 10.8 mm, a die size of 104 mm2, which amounts to about 80% of the size of the A10.[1]

It serves as a co-processor to its Intel based host, providing of facilities for handling a variety of functions not present in the host. It is designed to stay active even if the main computer is in a halted low power mode. The main application processor in T2 is running an operating system called bridgeOS.

The secondary processor in T2 is an 32-bit ARMv7-A based CPU called Secure Enclave Processor (SEP) which has the task of generating and storing encryption keys. It is running an operating system called "sepOS" based on the L4 microkernel.[5]

The T2 module is built as a package on a package (PoP) together with its own LP-DDR4 RAM. Mac configurations with 1 TB of SSD storage or greater receive 2 GB LP-DDR4, while lower storage configurations receive 1 GB.[6]

The bridgeOS of Apple T2 is stored in a firmware partition of the Mac's built-in SSD, which is hidden in macOS and Windows.[7]

The T2 communicates with the host via a USB-attached Ethernet port.[3]

Security features

There are numerous features regarding security, including:

• The SEP is used for handling and storing encryption keys, including keys for Touch ID, FileVault, macOS Keychain, and UEFI firmware passwords. It also stores the machine's unique ID (UID) and group ID (GID).[8][9][5]
• An AES Crypto Engine implementing AES-256 and a hardware random number generator.[5]
• A Public Key Accelerator is used to perform asymmetric cryptography operations like RSA and elliptic-curve cryptography.[5]
• A storage controller for the computer's solid-state drive, including always on, on-the-fly encryption and decryption of data to and from it.[4][9][10]

The T2 is integral in the boot sequence and upgrading of operating systems, not allowing unsigned components to interfere.[4][8][9][10]

Other features

There are other facilities present not directly associated with security.

• Controllers for microphones, camera, ambient light sensors and Touch ID.[8][9][10]
• Image coprocessor enabling accelerated image processing and quality enhancements such as color, exposure balance, and focus for the iMac Pro's FaceTime HD camera.[8][10]
• Video codec enabling accelerated encoding and decoding of H.264 and H.265.[11]
• Controller for a touchscreen, implemented as the Touch Bar in portable Macintosh computers.[9]
• Speech recognition used in the "Hey Siri" feature.[9]
• Monitoring and controlling of the machine state, including a system diagnose server and thermals management.[10][3]
• Speaker controller.[8][10]