Clarification on usage with atecc608a module and wolfMQTT

[Aareksio]

Hi,

I'm trying to setup raspberry pi with the most simple application that connects to AWS IoT using encryption provided by atecc608a.

Could you please provide updated example of usage with atecc608a module (and ideally further, with wolfMQTT)?

Reading through code, documentation and issues, I found myself lost, a few examples:

• not so long ago in an issue, it was revealed you use a fork of cryptoauth lib, branch named actatls, while in the changelog of source repository you may find a line: Removed atcatls related files as they were of limited value.

• it is unclear whether one should use pk_callbacks or ws_ecc_* API

• compiling with #include "wolfssl/wolfcrypt/port/atmel/atmel.h" as per example leads to undefined references

As my understanding of C code, not to mention wolfSSL, is fairly limited, I'd appreciate a working example or up-to-date clarification on how to use the library with the module.

[dgarske]

Hi Aareksio,

The CryptoAuthLib support for the atcatls API's were removed by Atmel, so we pulled them into a branch we have here:
https://github.com/dgarske/cryptoauthlib/tree/atcatls

The wolfSSL TLS use of the ATECC chip is currently supported via the PK callbacks (HAVE_PK_CALLBACKS). The best information can be found here:
https://github.com/wolfSSL/wolfssl/tree/master/wolfcrypt/src/port/atmel

You'll need to build with WOLFSSL_ATECC508A and HAVE_PK_CALLBACKS and call atcatls_set_callbacks(ctx) to setup the PK callbacks. To debug add WOLFSSL_ATECC508A_DEBUG.

The wolfCrypt_Init() function will call atmel_init() in atmel.c to setup the hardware. You can customize the ATECC slots using macros here: https://github.com/wolfSSL/wolfssl/blob/master/wolfssl/wolfcrypt/port/atmel/atmel.h#L47

Make sure and use the latest GitHub master as there were some recent ATECC fixes merged:
The following fixes have been made since release:
#2199
#2172
#2086
#2052
#2034

Thanks,
David Garske, wolfSSL