[PATCH] sm3: implement SM3 hash algorithm

[R0b0t1]

On Sat, Oct 14, 2017 at 12:05 PM, 张佳(乾越) <qianyue.zj at alibaba-inc.com> wrote:
> Hi Werner,
>
> This is the review request for SM3 hash algorithm. Plz see the commit
> header and patch for more details.
>
> SM3 hash algorithm is already accepted and supported by TPM 2.0 spec.
> So it is necessary to implement this algorithm in a famous open source
> software for checking the digest value computed by TPM.
>
> Plz refer to this PR (https://github.com/gpg/libgcrypt/pull/2) for code
> review.
>
> Thanks,
> Jia
>

Jia,

It is my understanding that SM3 was not accepted into any global TPM
specification and is merely mandated for use within China.

My research on SM3 has turned up only one detailed cryptanalysis of
the function.[1] That cryptanalysis implies that the techniques used
to "strengthen" SM3 do not accomplish what the creators claim, and may
even weaken the hash function when compared to its inspiration, SHA-2.

Less detailed analysis[3] of the claims presented by the creators
reflect poorly on their work. For starters, none of the techniques
meant to increase the security of SM3 are explained. Their utility is
unknown, and a cursory glance shows that in at least one case a round
operation is simplified. Perhaps more distressing is the selection of
constants with no justification.

It seems very likely that the algorithm has undisclosed backdoors.

Also pertinent is the existence of GmSSL,[3] a fork of OpenSSL which
contains various cryptographic standards developed by the Chinese
government that were, presumably, not deemed fit for inclusion in
OpenSSL.

Inclusion of weak cryptography in gcrypt would be a disservice to
those users which trust gcrypt with their life. I understand I am not
the person to whom you addressed your message, nor am I a gcrypt
developer, but I felt it necessary to reply to this conversation.

Respectfully,
     R0b0t1


[1]: https://eprint.iacr.org/2012/274.pdf, also attached.
[2]: https://tinycrypt.wordpress.com/2017/02/22/asmcodes-sm3/
[3]: http://gmssl.org/
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