Overview

The Read Protection (RDP) feature is used to encrypt the Trustzone secure firmware (image3) of the Cortex-M core, preventing secure world code from being accessed by the non-secure world. The secure world firmware is stored in encrypted form in Flash. This firmware has two modes of operation:

• For SoCs that do not support Flash address security isolation: It is decrypted and loaded into secure SRAM or PSRAM in the secure Bootloader before execution.

• For SoCs that support Flash address security isolation: In addition to loading into secure SRAM for execution, it also supports execution in XiP mode at secure Flash addresses.

Note

For Cortex-A core SoCs, it is recommended to use the ATF encryption service.