Provides the library for Microchip CryptoAuth devices. More...

Detailed Description

Provides the library for Microchip CryptoAuth devices.

See also: https://github.com/MicrochipTech/cryptoauthlib

Introduction

This package provides support for the official library for Microchip CryptoAuth devices.

Warning

Some functions can only be used, when the data, config and otp zones of the device are locked. Locking is permanent and cannot be undone. Be careful if you're not sure you've configured everything correctly. For more information we refer to the data sheet of the device.

Usage

Add USEPKG += cryptoauthlib to your Makefile.

Shell

To facilitate the device configuration the RIOT shell provides some helper commands. Currently there are shell commands to read the device's config zone, to lock the config zone (this will lock the config zone permanently and cannot be undone) and to check whether config and data zone are locked. The shell handler is enabled, if cryptoauthlib is included as a package in the Makefile of an application that also includes the shell (e.g. examples/default).

No poll mode

After sending a command to the device, responses are usually polled to enable quicker response times. Alternatively ATCA_NO_POLL can be enabled through CFLAGS to simply wait for the max execution time of a command before reading the response.

Implementation status

This implementation was partly tested with ATECC508A and ATECC608A devices. We haven't tested the functions that require locking the device, yet. There's a wrapper in the cryptoauthlib/contrib folder, which implements most of the HAL functions. Currently the functions hal_i2c_discover_devices and hal_i2c_discover_buses are unimplemented, as well as hal_i2c_post_init.

Wake function

The wake function only works when a 0x00 byte is sent on an i2c interface that runs with with 133kHz or less. Currently RIOT sets the baudrate to the default value of 100 kHz and there's no interface to change that. If the default speed ever changes to a value higher than 133 kHz the wake function needs to be adapted. For more information on how to send a proper wake condition we refer to the data sheet of the device.

Tests

The library provides unittests for the library functions. There is a directory called "pkg_cryptoauthlib_internal_tests" in the RIOT testfolder which runs part of the unittests. Some of the provided tests can only be run when the config, data and/or otp zones of the device are locked. Some tests (but not all) will automatically lock zones as needed. We omit those tests at the moment, because zones can only be locked permanently. Unlocking is not possible! Also there is a test for comparing the runtime of the RIOT software implementation and the CryptoAuth hardware implementation for calculating a SHA-256 hash value.

Files
file	atca.h
	Default addresses and device descriptor for CryptoAuth devices.

file	atca_params.h
	Default configuration for Microchip CryptoAuth devices.

file	cryptoauthlib_test.h