Re: [RFC PATCH 1/2] rust: crypto: add library AES-128 / SHA-256 / HMAC-SHA256 bindings

[Eric Biggers <ebiggers@kernel.org>]

On Wed, Jun 17, 2026 at 04:01:32PM +0100, Mike Lothian wrote:
> +/*
> + * AES-128 single-block ECB encryption: out = AES(key, in).
> + *
> + * A helper because aes_encrypt() takes a transparent union (aes_encrypt_arg)
> + * that bindgen cannot express. SHA-256 and HMAC-SHA256 are plain extern
> + * functions and are bound directly.
> + */
> +__rust_helper int
> +rust_helper_aes128_encrypt_block(const u8 *key, const u8 *in, u8 *out)
> +{
> +	struct aes_enckey enckey;
> +	int ret;
> +
> +	ret = aes_prepareenckey(&enckey, key, AES_KEYSIZE_128);
> +	if (ret)
> +		return ret;
> +	aes_encrypt(&enckey, out, in);
> +	memzero_explicit(&enckey, sizeof(enckey));
> +	return 0;
> +}

This is kind of an anti-pattern, both in expanding the key for every
block and also exposing bare AES instead of AES modes of operation.
It's true that lib/crypto/ is missing a lot of AES modes (I'm working on
that), but AES-CMAC is there already which is one of the two you need.

- Eric