diff --git a/features/cryptocell/FEATURE_CRYPTOCELL310/Readme.md b/features/cryptocell/FEATURE_CRYPTOCELL310/Readme.md index a91c95ec3c..f8145b5a35 100644 --- a/features/cryptocell/FEATURE_CRYPTOCELL310/Readme.md +++ b/features/cryptocell/FEATURE_CRYPTOCELL310/Readme.md @@ -1,38 +1,37 @@ # 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. +Cryptocell (CC) 310 is a hardware accelerator you can port to boards that 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`) +* 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 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: +To port your CC 310 driver to Mbed OS on your specific target: -1. In `targets.json` add the following to your target: +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)`. 1. In `objects.h`, include `objects_cryptocell.h`. You can use the `FEATURE_CRYPTOCELL310` precompilation check as defined above. 1. In `features/cryptocell/FEATURE_CRYPTOCELL310/TARGET_`, add your platform-specific libraries for all toolchains in `TOOLCHAIN_ARM`, `TOOLCHAIN_GCC_ARM` and `TOOLCHAIN_IAR` respectively. 1. 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. + * 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()` in these functions. * Define `crypto_platform_ctx` in `crypto_device_platform.h` in a way that suits your implementation. ## Enabling optional alternative drivers -There are three additional modules that have alternative implementation support, which are not enabled by default. -The reason is to allow backwards compatability, as these modules don't have full functionality, and return `MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED` for some features. -The modules are: -* `AES` which only supports 128 bit key size, in opposed to previous support for all key sizes. -* `CMAC` which only supports AES 128 bit key size, in opposed to previous supporting DES and all key sizes. -* `SHA512` which only supports SHA512, in opposed to previously supporting SHA384 as well. +Three additional modules that are not enabled by default have alternative implementation support. This allows backward compatability because these modules don't have full functionality and returns `MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED` for some features. The modules are: -In order to enable these modules, you should define `MBEDTLS_AES_ALT`, `MBEDTLS_CMAC_ALT` and `MBEDTLS_SHA512_ALT` respectively, either in `mbed_app.json` or in your `MBEDTLS_USER_CONFIG_FILE` to have hardware accelerated module with reduced RAM size, on the expense of full functionality. +* `AES`, which only supports 128 bit key size, as opposed to previous support for all key sizes. +* `CMAC`, which only supports AES 128 bit key size, as opposed to previous support for DES and all key sizes. +* `SHA512`, which only supports SHA512, as opposed to previous support for SHA384, as well. + +To enable these modules, define `MBEDTLS_AES_ALT`, `MBEDTLS_CMAC_ALT` and `MBEDTLS_SHA512_ALT`, either in `mbed_app.json` or in your `MBEDTLS_USER_CONFIG_FILE`, to have hardware accelerated module with reduced RAM size, on the expense of full functionality.