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Subject: Re: [PATCH v9 3/7] crypto: move curve_id of ECDH from the key to
 algorithm name
To:     <Tudor.Ambarus@microchip.com>, <herbert@gondor.apana.org.au>,
        <davem@davemloft.net>, <marcel@holtmann.org>,
        <johan.hedberg@gmail.com>, <luiz.dentz@gmail.com>
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        <wangzhou1@hisilicon.com>, <linux-kernel@vger.kernel.org>,
        <Nicolas.Ferre@microchip.com>
References: <1614064219-40701-1-git-send-email-yumeng18@huawei.com>
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From:   yumeng <yumeng18@huawei.com>
Message-ID: <fd3b7c0f-d7f2-3d27-cfef-98ec3614dd1a@huawei.com>
Date:   Wed, 24 Feb 2021 09:29:34 +0800
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在 2021/2/23 18:44, Tudor.Ambarus@microchip.com 写道:
> Hi,
> 
> On 2/23/21 9:10 AM, Meng Yu wrote:
>> --- a/drivers/crypto/atmel-ecc.c
>> +++ b/drivers/crypto/atmel-ecc.c
>> @@ -104,7 +104,7 @@ static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
>>                  return -EINVAL;
>>          }
>>
>> -       ctx->n_sz = atmel_ecdh_supported_curve(params.curve_id);
>> +       ctx->n_sz = atmel_ecdh_supported_curve(ctx->curve_id);
>>          if (!ctx->n_sz || params.key_size) {
>>                  /* fallback to ecdh software implementation */
>>                  ctx->do_fallback = true;
> 
> Now that you moved the curve id info into the alg name, and it is
> no longer dynamically discovered when decoding the key, does it
> still make sense to keep the curve id, the key size checks, and
> the fallback to the software implementation?
>I think we can keep the curve id, the key size check if 'atmel-ecc' may
support other curves in the future, and if you're sure P256 is the only
curve 'atmel-ecc' uses, and it will be changed, we can delete it.

And fallback to ecdh software implementation is needed when
params.key_size is zero.

> I don't have an atecc508 at hand to test the changes, but I expect
> your changes won't affect the functionality.
> 

OK, if you or your team members have an atecc508, please help test.