Problem:

A common pattern is:

GUARD(s2n_stuffer_skip_write(stuffer, bytes_to_write));
uint8_t* ptr = suffer->blob.data + stuffer->write_cursor - bytes_to_write;

which could be simplified.

Solution:

*ptr could be an *out parameter to s2n_stuffer_skip_write

• Does this change what S2N sends over the wire? No.
• Does this change any public APIs? No.

This line describing the return value PSA_ERROR_INVALID_SIZE for psa_its_get should be deleted:

https://github.com/ARMmbed/mbedtls/blob/development/library/psa_crypto_its.h#L102

• There is no error code PSA_ERROR_INVALID_SIZE.
• There is no argument data_size.
• It is not an error to ask for just part of the data.

(Also, the description of PSA_ERROR_INVALID_ARGUMENT does not

https://scotthelme.co.uk/a-new-security-header-feature-policy/

I guess it will be easy to add, because we certainly don't use any of these features.
Or maybe "gyroscope" or so may be used by the random number generator in sjcl, but that's all.

Please add provider support for the "botan encryption" command and implement the needed AES operations with PKCS#11.
I could not find any command line tool that I can use for that. OpenSSL's PKCS#11 engine does not support AES either.