Re: [PATCH 1/3] crypto: sm4 - create SM4 library based on sm4 generic code

[Tianjia Zhang <tianjia.zhang@linux.alibaba.com>]

Hi Eric,

On 6/11/21 7:19 AM, Eric Biggers wrote:
> 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.
> 

Thanks for your suggestion, will do in the next version patch.

>> 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.

Ditto. thanks for pointing it out.

> 
> - Eric
> 

Best regards,
Tianjia