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Date:   Thu, 10 Jun 2021 16:19:36 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Gilad Ben-Yossef <gilad@benyossef.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        "Markku-Juhani O . Saarinen" <mjos@iki.fi>,
        Jussi Kivilinna <jussi.kivilinna@iki.fi>, x86@kernel.org,
        linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] crypto: sm4 - create SM4 library based on sm4
 generic code
Message-ID: <YMKeCIfSWZCVX+BT@gmail.com>
References: <20210610134459.28541-1-tianjia.zhang@linux.alibaba.com>
 <20210610134459.28541-2-tianjia.zhang@linux.alibaba.com>
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On Thu, Jun 10, 2021 at 09:44:57PM +0800, Tianjia Zhang wrote:
> Take the existing small footprint and mostly time invariant C code

It is using an S-box without any prefetching.  That doesn't look very
"time invariant" to me.

> diff --git a/lib/crypto/sm4.c b/lib/crypto/sm4.c
> new file mode 100644
> index 000000000000..cbdd14a254d0
[..]
> +/**
> + * crypto_sm4_expand_key - Expands the SM4 key as described in GB/T 32907-2016
> + * @ctx:	The location where the computed key will be stored.
> + * @in_key:	The supplied key.
> + * @key_len:	The length of the supplied key.
> + *
> + * Returns 0 on success. The function fails only if an invalid key size (or
> + * pointer) is supplied.
> + */
> +int crypto_sm4_expand_key(struct crypto_sm4_ctx *ctx, const u8 *in_key,
> +			  unsigned int key_len)
[...]
> +/**
> + * crypto_sm4_do_crypt - Encrypt or decrypt a single SM4 block
> + * @rk:		The rkey_enc for encrypt or rkey_dec for decrypt
> + * @out:	Buffer to store output data
> + * @in: 	Buffer containing the input data
> + */
> +void crypto_sm4_do_crypt(const u32 *rk, u8 *out, const u8 *in)

Calling these "sm4_expandkey()" and "sm4_crypt_block()" would be more consistent
with the other lib/crypto/ functions such as the AES ones.  The other
lib/crypto/ functions don't have a "crypto_" prefix, as that is used for
functions related to the traditional crypto API rather than the library API.

- Eric