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FEATURE_CRYPTOCELL310

Guidelines for porting Cryptocell to Mbed OS

Cryptocell (CC) 310 is a hardware accelerator that can be ported to several boards, assuming these boards have CC 310 embedded in their hardware.

The CC 310 driver consists of three libraries:

  • A common core library(libcc_core.a).
  • A platform-specific TRNG library, containing TRNG-related information, for sampling sufficient entropy on the specific platform(libcc_trng.a).
  • A platform-specific library containing extra information, such as the CC register's base addresses on the specific board. (libcc_ext.a)

Library version information:

  • The CC 310 libraries were built from version arm_sw-cc310-1.1.0.1285
  • The IAR libraries were built using IAR ANSI C/C++ Compiler V7.80.1.11864/W32 for ARM with --cpu Cortex-M4f.
  • The ARM libraries were built using ARM Compiler 5.06 update 4 (build 422) with --cpu cortex-m4.
  • The GCC_ARM libraries were built using arm-none-eabi-gcc 6.3.1 20170620 (release) with -mcpu=cortex-m4.

To port your CC 310 driver to Mbed OS on your specific target, do the following:

  1. In targets.json add the following to your target:
    • MBEDTLS_CONFIG_HW_SUPPORT to macros_add key. This instructs Mbed TLS to look for an alternative cryptographic implementation.
    • CRYPTOCELL310 to feature. Use this in your common code that you need to remove from compilation in case CC exists in your board. Use #if !defined(FEATURE_CRYPTOCELL310) and #if defined(FEATURE_CRYPTOCELL310).
  2. In objects.h, include objects_cryptocell.h. You can use the FEATURE_CRYPTOCELL310 precompilation check as defined above.
  3. In features/cryptocell/FEATURE_CRYPTOCELL310/TARGET_<target name>, add your platform-specific libraries for all toolchains in TOOLCHAIN_ARM, TOOLCHAIN_GCC_ARM and TOOLCHAIN_IAR respectively.
  4. Add your CC setup code:
    • Implement crypto_platform_setup() and crypto_platform_terminate() to enable CC on your platform, in case you have board-specific setup functionality, required for CC setup. You MUST call 'SaSi_LibInit()` and 'SaSi_LibFini()' respectively in these functions.
    • Define crypto_platform_ctx in crypto_device_platform.h in a way that suits your implementation.