STM32L476 how to add cryptolib to micropython ?

[julien-minet]

Hello,

how to add cryptolib to Micropython for an STM32L476? I'm stuck...

I need to use cryptolib to send data in LoraWan with an STM32L476 + SX1276.
First I added in the file port/stm32/mpconfigport.h below the line:

#define MICROPY_PY_CRYPTOLIB (MICROPY_PY_SSL)

+ #define MICROPY_PY_SSL (1)    

I have several errors at the end of compilation ../../extmod/modcryptolib.c

../../extmod/modcryptolib.c:84:5: error: unknown type name 'AES_CTX_IMPL'
   84 |     AES_CTX_IMPL ctx;
      |     ^~~~~~~~~~~~
../../extmod/modcryptolib.c: In function 'cryptolib_aes_make_new':
../../extmod/modcryptolib.c:258:5: error: implicit declaration of function 'aes_initial_set_key_impl' [-Werror=implicit-function-declaration]
  258 |     aes_initial_set_key_impl(&o->ctx, keyinfo.buf, keyinfo.len, ivinfo.buf);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~
../../extmod/modcryptolib.c: In function 'aes_process':
../../extmod/modcryptolib.c:297:9: error: implicit declaration of function 'aes_final_set_key_impl' [-Werror=implicit-function-declaration]
  297 |         aes_final_set_key_impl(&self->ctx, encrypt_mode);
      |         ^~~~~~~~~~~~~~~~~~~~~~
../../extmod/modcryptolib.c:312:17: error: implicit declaration of function 'aes_process_ecb_impl' [-Werror=implicit-function-declaration]
  312 |                 aes_process_ecb_impl(&self->ctx, in, out, encrypt);
      |                 ^~~~~~~~~~~~~~~~~~~~
../../extmod/modcryptolib.c:318:13: error: implicit declaration of function 'aes_process_cbc_impl' [-Werror=implicit-function-declaration]
  318 |             aes_process_cbc_impl(&self->ctx, in_bufinfo.buf, out_buf_ptr, in_bufinfo.len, encrypt);
      |             ^~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
-e See https://github.com/micropython/micropython/wiki/Build-Troubleshooting
make: *** [../../py/mkrules.mk:90 : build-NUCLEO_L476RG/extmod/modcryptolib.o] Erreur 1

Then I added :

git submodule update --init -- lib/mbedlts
+ in mpconfigport.h 
+ #define MICROPY_SSL_MBEDTLS (1)

and then I get an error at the start of compilation:

Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
GEN build-NUCLEO_L476RG/genhdr/qstr.i.last
../../extmod/modcryptolib.c:64:10: fatal error: mbedtls/aes.h: No such file or directory
   64 | #include <mbedtls/aes.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.
../../extmod/modhashlib.c:35:10: fatal error: mbedtls/version.h: No such file or directory
   35 | #include "mbedtls/version.h"
      |          ^~~~~~~~~~~~~~~~~~~
compilation terminated.
../../extmod/modtls_mbedtls.c:43:10: fatal error: mbedtls/platform.h: No such file or directory
   43 | #include "mbedtls/platform.h"
      |          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.

[julien-minet]

I found the solution:

1- in /micropython:

git submodule update --init -- lib/mbedlts

2- Apparently, you don't need to modify stm32/mpconfigport.h.... directly, but rather add the following two lines to the file corresponding to the board (here NUCLEO_L476RG):

ports/stm32/boards/NUCLEO_L476RG/mpconfigboard.mk

# MicroPython settings
MICROPY_PY_SSL = 1
MICROPY_SSL_MBEDTLS = 1

3- make BOARD=NUCLEO_L476RG submodules
4- make BOARD=NUCLEO_L476RG

And the compilation is complete....

[jonnor]

Super. And thanks for documenting the fix! This will help future travellers :)