What is the Public Key Accelerator?

It is secure

The Public Key Accelerator uses a combination of the device’s UID and a hash of sepOS, which is provided by the Secure Enclave Boot ROM or (on Apple A10 and later SoCs) by the Secure Enclave Boot Monitor. This is referred to as an OS-bound key, and is designed to improve security of passcode-protected data in case critical changes are made to sepOS without the user’s authorization.

At startup, the TRNG generates an ephemeral wrapping key, which is used by sepOS to wrap file keys for use by the Application Processor’s file-system driver. The wrapped key is never exposed to software outside the Secure Enclave,TrustWallet DApps Support , so it cannot be guessed or copied by malware.