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.

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.

In crypto_sizes.h we rely on the fact that the largest block size is a multiple of all possible block sizes when we compute maximum output lengths by rounding up to a multiple of the maximum block size. (This would not be correct if the largest block size was not a multiple of the others: for example if 8, 12 and 16 are possible block sizes the length to round up is say 13, then the maximum will

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.