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CryptoAuthLib - Microchip CryptoAuthentication Library {#mainpage}


This library implements the APIs required to communicate with Microchip Security device. The family of devices supported currently are:

The best place to start is with the Microchip Trust Platform

Online API documentation is at

Latest software and examples can be found at:

Prerequisite hardware to run CryptoAuthLib examples:

Alternatively a Microchip MCU and Adapter Board:

For most development, using socketed top-boards is preferable until your configuration is well tested, then you can commit it to a CryptoAuth Xplained Pro Extension, for example. Keep in mind that once you lock a device, it will not be changeable.



In order to properly configured the library there must be a header file in your project named atca_config.h at minimum this needs to contain defines for the hal and device types being used. Most integrations have an configuration mechanism for generating this file. See the template which is configured by CMake for Linux, MacOS, & Windows projects.

An example of the configuration:

/* Cryptoauthlib Configuration File */

/* Include HALS */
#define ATCA_HAL_I2C

/* Included device support */

/* \brief How long to wait after an initial wake failure for the POST to
 *         complete.
 * If Power-on self test (POST) is enabled, the self test will run on waking
 * from sleep or during power-on, which delays the wake reply.

#endif // ATCA_CONFIG_H

There are two major compiler defines that affect the operation of the library.

  • ATCA_NO_POLL can be used to revert to a non-polling mechanism for device responses. Normally responses are polled for after sending a command, giving quicker response times. However, if ATCA_NO_POLL is defined, then the library will simply delay the max execution time of a command before reading the response.
  • ATCA_NO_HEAP can be used to remove the use of malloc/free from the main library. This can be helpful for smaller MCUs that don't have a heap implemented. If just using the basic API, then there shouldn't be any code changes required. The lower-level API will no longer use the new/delete functions and the init/release functions should be used directly.

Some specific options are available in the fully documented configuration files lib/calib/calib_config.h, atca_configuration.h, lib/crypto/crypto_config.h, lib/host/atca_host_config.h which is also the place where features can be selected. We provide some configurations focused on specific use cases and the checks are enabled by default.

Release notes

See Release Notes

Host Device Support

CryptoAuthLib will run on a variety of platforms from small micro-controllers to desktop host systems. See hal readme

If you have specific microcontrollers or platforms you need support for, please contact us through the Microchip portal with your request.

CryptoAuthLib Architecture

Cryptoauthlib API documentation is at

The library is structured to support portability to:

  • multiple hardware/microcontroller platforms
  • multiple environments including bare-metal, RTOS and Windows/Linux/MacOS
  • multiple chip communication protocols (I2C, SPI, and SWI)

All platform dependencies are contained within the HAL (hardware abstraction layer).

Directory Structure

lib - primary library source code
lib/atcacert - certificate data and i/o methods
lib/calib - the Basic Cryptoauth API
lib/crypto - Software crypto implementations external crypto libraries support (primarily SHA1 and SHA256)
lib/hal - hardware abstraction layer code for supporting specific platforms
lib/host - support functions for common host-side calculations
lib/jwt - json web token functions
test - Integration test and examples. See test/cmd-processor.c for main() implementation.

For production code, test directories should be excluded by not compiling it
into a project, so it is up to the developer to include or not as needed.  Test
code adds significant bulk to an application - it's not intended to be included
in production code.


There is a set of integration tests found in the test directory which will at least partially demonstrate the use of the objects. Some tests may depend upon a certain device being configured in a certain way and may not work for all devices or specific configurations of the device. See test readme

Using CryptoAuthLib (Microchip CryptoAuth Library)

The best place to start is with the Microchip Trust Platform

Also application examples are included as part of the Harmony 3 framework and can be copied from the Harmony Content Manager or found with the Harmony 3 Framework Cryptoauthlib_apps

Incorporating CryptoAuthLib in a Linux project using USB HID devices

The Linux HID HAL files use the Linux udev development software package.

To install the udev development package under Ubuntu Linux, please type the following command at the terminal window:

sudo apt-get install libudev-dev

This adds the udev development development software package to the Ubuntu Linux installation.

The Linux HID HAL files also require a udev rule to be added to change the permissions of the USB HID Devices. Please add a new udev rule for the Microchip CryptoAuth USB devices.

cd /etc/udev/rules.d
sudo touch mchp-cryptoauth.rules

Edit the mchp-cryptoauth.rules file and add the following line to the file:

SUBSYSTEM=="hidraw", ATTRS{idVendor}=="03eb", ATTRS{idProduct}=="2312", MODE="0666"


Library for interacting with the Crypto Authentication secure elements



Security policy





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