Re: [PATCH 1/2] crypto: sm3 - add a new alias name sm3-256

Eric Biggers
2020-02-10T03:17:31Z

On Fri, Feb 07, 2020 at 05:22:18PM +0800, Tianjia Zhang wrote:
> The name sm3-256 is defined in hash_algo_name in hash_info, but the
> algorithm name implemented in sm3_generic.c is sm3, which will cause
> the sm3-256 algorithm to be not found in some application scenarios of
> the hash algorithm, and an ENOENT error will occur. For example,
> IMA, keys, and other subsystems that reference hash_algo_name cannot use
> the hash algorithm of sm3. This patch adds an alias name sm3-256 to sm3,
> which can better solve the above problems.
>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
> crypto/sm3_generic.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/crypto/sm3_generic.c b/crypto/sm3_generic.c
> index 3468975215ca..ded41031bd5f 100644
> --- a/crypto/sm3_generic.c
> +++ b/crypto/sm3_generic.c
> @@ -163,7 +163,7 @@ int crypto_sm3_finup(struct shash_desc *desc, const u8 *data,
> }
> EXPORT_SYMBOL(crypto_sm3_finup);
>
> -static struct shash_alg sm3_alg = {
> +static struct shash_alg sm3_algs[2] = { {
> .digestsize = SM3_DIGEST_SIZE,
> .init = sm3_base_init,
> .update = crypto_sm3_update,
> @@ -176,16 +176,28 @@ static struct shash_alg sm3_alg = {
> .cra_blocksize = SM3_BLOCK_SIZE,
> .cra_module = THIS_MODULE,
> }
> -};
> +}, {
> + .digestsize = SM3_DIGEST_SIZE,
> + .init = sm3_base_init,
> + .update = crypto_sm3_update,
> + .final = sm3_final,
> + .finup = crypto_sm3_finup,
> + .descsize = sizeof(struct sm3_state),
> + .base = {
> + .cra_name = "sm3-256",
> + .cra_blocksize = SM3_BLOCK_SIZE,
> + .cra_module = THIS_MODULE,
> + }
> +} };

According to https://tools.ietf.org/id/draft-oscca-cfrg-sm3-01.html,
SM3 always produces a 256-bit hash value. E.g., it says:

"SM3 produces an output hash value of 256 bits long"

and

"SM3 is a hash function that generates a 256-bit hash value."

I don't see any mention of "SM3-256".

So why not just keep it as "sm3" and change hash_info.c instead?
Since the name there is currently wrong, no one can be using it yet.

- Eric