linux-kernel - Re: [PATCH v3 13/18] crypto: rsa-psspad: Get signature parameters from a given signature

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Date:   Mon, 5 Jul 2021 11:39:10 +0200
From:   Varad Gautam <varad.gautam@...e.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
CC:     linux-crypto@...r.kernel.org, dhowells@...hat.com,
        davem@...emloft.net, vt@...linux.org,
        tianjia.zhang@...ux.alibaba.com, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org, jarkko@...nel.org
Subject: Re: [PATCH v3 13/18] crypto: rsa-psspad: Get signature parameters
 from a given signature

Hi Herbert,

On 5/14/21 12:45 PM, Herbert Xu wrote:
> On Tue, Apr 20, 2021 at 01:41:18PM +0200, Varad Gautam wrote:
>>
>> +static int psspad_set_sig_params(struct crypto_akcipher *tfm,
>> +				 const void *sig,
>> +				 unsigned int siglen)
>> +{
>> +	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
>> +	struct rsapad_inst_ctx *ictx = akcipher_instance_ctx(inst);
>> +	const struct public_key_signature *s = sig;
>> +
>> +	if (!sig)
>> +		return -EINVAL;
>> +
>> +	ictx->salt_len = s->salt_length;
>> +	ictx->mgf_hash_algo = s->mgf_hash_algo;
> 
> Is there any reason why this couldn't be embedded into the key
> instead?

Sorry about the delay, do you mean setting these as part of
rsapad_set_pub_key()? 

The same pubkey can be used to verify both PSS and PKCSv1.5 style signatures,
so I don't see the signature params (salt length / mgf hash) being a part
of the pkey state.

Thanks,
Varad

> 
> Thanks,
> 

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