![]() ![]() The Secure Enclave includes a dedicated Secure Enclave Boot ROM. ![]() The result is strong memory protection without performance or software complexity tradeoffs. The Secure Enclave reads and writes memory as if it were regular unencrypted DRAM, whereas an observer outside the Secure Enclave sees only the encrypted and authenticated version of the memory. The Memory Protection Engine operates inline and transparently to the Secure Enclave. The first is used for data private to the Secure Enclave, and the second is used for data shared with the Secure Neural Engine. On Apple A14, A15, the M1 family, and later SoCS, the Memory Protection Engine supports two ephemeral memory protection keys. Nonce mismatches are handled similarly to authentication tag mismatches. For reads, the Memory Protection Engine verifies the nonce and each level of the integrity tree up to the SRAM. For writes, the Memory Protection Engine updates the nonce and each level of the integrity tree up to the SRAM. The nonces for all memory blocks are protected using an integrity tree rooted in dedicated SRAM within the Secure Enclave. The nonce is used as an additional tweak for the CMAC authentication tag. To help prevent replay of security-critical data, the Memory Protection Engine stores a unique one-off number, called a nonce, for the block of memory alongside the authentication tag. Starting with the Apple A11 and S4 SoCs, the Memory Protection Engine adds replay protection for Secure Enclave memory. After a memory authentication error, the Secure Enclave stops accepting requests until the system is rebooted. If the tag doesn’t match, the Memory Protection Engine signals an error to the Secure Enclave. If the authentication tag matches, the Memory Protection Engine decrypts the block of memory. When the Secure Enclave reads the memory, the Memory Protection Engine verifies the authentication tag. The Memory Protection Engine stores the authentication tag alongside the encrypted memory. Whenever the Secure Enclave writes to its dedicated memory region, the Memory Protection Engine encrypts the block of memory using AES in Mac XEX (xor-encrypt-xor) mode, and calculates a Cipher-based Message Authentication Code (CMAC) authentication tag for the memory. When the device starts up, the Secure Enclave Boot ROM generates a random ephemeral memory protection key for the Memory Protection Engine. ![]() Multiple layers of protection isolate the Secure Enclave protected memory from the Application Processor. The Secure Enclave operates from a dedicated region of the device’s DRAM memory. Intel-based Mac computers that contain the Apple T2 Security Chip MacBook Pro computers with Touch Bar (20) that contain the Apple T1 Chip The Secure Enclave is a hardware feature of most versions of iPhone, iPad, Mac, Apple TV, Apple Watch, and HomePod-namely: Although the Secure Enclave doesn’t include storage, it has a mechanism to store information securely on attached storage separate from the NAND flash storage that’s used by the Application Processor and operating system. It follows the same design principles as the SoC does-a boot ROM to establish a hardware root of trust, an AES engine for efficient and secure cryptographic operations, and protected memory. The Secure Enclave is isolated from the main processor to provide an extra layer of security and is designed to keep sensitive user data secure even when the Application Processor kernel becomes compromised. The Secure Enclave is a dedicated secure subsystem integrated into Apple systems on chip (SoCs). iPhone Text Message Forwarding security.How iMessage sends and receives messages.Adding transit and eMoney cards to Apple Wallet.Rendering cards unusable with Apple Pay.Adding credit or debit cards to Apple Pay.How Apple Pay keeps users’ purchases protected.Intro to app security for iOS and iPadOS.Protecting access to user’s health data.How Apple protects users’ personal data.Activating data connections securely in iOS and iPadOS.Protecting user data in the face of attack.Protecting keys in alternate boot modes.Encryption and Data Protection overview.UEFI firmware security in an Intel-based Mac.Additional macOS system security capabilities.recoveryOS and diagnostics environments.Contents of a LocalPolicy file for a Mac with Apple silicon.LocalPolicy signing-key creation and management.Boot process for iOS and iPadOS devices.Secure intent and connections to the Secure Enclave.Face ID, Touch ID, passcodes, and passwords. ![]()
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