linux-kernel - Re: [PATCH v5 04/10] crypto: akcipher - new verify API for public key algorithms

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Date:   Wed, 27 Feb 2019 18:28:37 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Vitaly Chikunov <vt@...linux.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        David Howells <dhowells@...hat.com>,
        linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 04/10] crypto: akcipher - new verify API for public
 key algorithms

Hi Vitaly,

On Sun, 2019-02-24 at 09:08 +0300, Vitaly Chikunov wrote:
> Previous akcipher .verify() just `decrypts' (using RSA encrypt which is
> using public key) signature to uncover message hash, which was then
> compared in upper level public_key_verify_signature() with the expected
> hash value, which itself was never passed into verify().
> 
> This approach was incompatible with EC-DSA family of algorithms,
> because, to verify a signature EC-DSA algorithm also needs a hash value
> as input; then it's used (together with a signature divided into halves
> `r||s') to produce a witness value, which is then compared with `r' to
> determine if the signature is correct. Thus, for EC-DSA, nor
> requirements of .verify() itself, nor its output expectations in
> public_key_verify_signature() wasn't sufficient.
> 
> Make improved .verify() call which gets hash value as input and produce
> complete signature check without any output besides status.
> 
> Now for the top level verification only crypto_akcipher_verify() needs
> to be called.

All but this patch apply.  Which branch is this patch based against?

Mimi