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Message-ID: <24151f46-e7b3-434b-88e3-b53ac783eb13@linux.ibm.com>
Date: Sun, 3 Mar 2024 16:03:02 -0500
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Subject: Re: [PATCH v4 11/12] crypto: asymmetric_keys - Adjust signature size
 calculation for NIST P521
Content-Language: en-US
To: Lukas Wunner <lukas@wunner.de>
Cc: keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
        herbert@gondor.apana.org.au, davem@davemloft.net,
        linux-kernel@vger.kernel.org, saulo.alessandre@tse.jus.br
References: <20240301022007.344948-1-stefanb@linux.ibm.com>
 <20240301022007.344948-12-stefanb@linux.ibm.com>
 <20240303184745.GA9392@wunner.de>
From: Stefan Berger <stefanb@linux.ibm.com>
In-Reply-To: <20240303184745.GA9392@wunner.de>
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On 3/3/24 13:47, Lukas Wunner wrote:
> On Thu, Feb 29, 2024 at 09:20:06PM -0500, Stefan Berger wrote:
>> Adjust the calculation of the maximum signature size for support of
>> NIST P521. While existing curves may prepend a 0 byte to their coordinates
>> (to make the number positive), NIST P521 will not do this since only the
>> first bit in the most significant byte is used.
>>
>> If the encoding of the x & y coordinates requires more than 128 bytes then
>> an additional byte is needed for the encoding of the length. Take this into
>> account when calculating the maximum signature size.
>>
>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> 
> Reviewed-by: Lukas Wunner <lukas@wunner.de>
> 
Thanks. I have to adjust the commit text and comment in the patch, 
though. It should be '... requires at least 128 bytes then ...'