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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Mon, 26 Jun 2023 11:21:20 +0200
Message-ID: <CAMj1kXHcDrL5YexGjwvHHY0UE1ES-KG=68ZJr7U=Ub5gzbaePg@mail.gmail.com>
Subject: Re: [v2 PATCH 0/5] crypto: Add akcipher interface without SGs
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     David Howells <dhowells@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Roberto Sassu <roberto.sassu@huaweicloud.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Stefan Berger <stefanb@linux.ibm.com>,
        Mimi Zohar <zohar@linux.ibm.com>, dmitry.kasatkin@gmail.com,
        Jarkko Sakkinen <jarkko@kernel.org>, keyrings@vger.kernel.org,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
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On Thu, 15 Jun 2023 at 12:26, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> v2 changes:
>
> - Rename dsa to sig.
> - Add braces around else clause.
>
> The crypto akcipher interface has exactly one user, the keyring
> subsystem.  That user only deals with kernel pointers, not SG lists.
> Therefore the use of SG lists in the akcipher interface is
> completely pointless.
>
> As there is only one user, changing it isn't that hard.  This
> patch series is a first step in that direction.  It introduces
> a new interface for encryption and decryption without SG lists:
>
> int crypto_akcipher_sync_encrypt(struct crypto_akcipher *tfm,
>                                  const void *src, unsigned int slen,
>                                  void *dst, unsigned int dlen);
>
> int crypto_akcipher_sync_decrypt(struct crypto_akcipher *tfm,
>                                  const void *src, unsigned int slen,
>                                  void *dst, unsigned int dlen);
>
> I've decided to split out signing and verification because most
> (all but one) of our signature algorithms do not support encryption
> or decryption.  These can now be accessed through the sig interface:
>
> int crypto_sig_sign(struct crypto_sig *tfm,
>                     const void *src, unsigned int slen,
>                     void *dst, unsigned int dlen);
>
> int crypto_sig_verify(struct crypto_sig *tfm,
>                       const void *src, unsigned int slen,
>                       const void *digest, unsigned int dlen);
>
> The keyring system has been converted to this interface.
>

This looks like a worthwhile improvement to me.

As I asked before, could we do the same for the acomp API? The only
existing user blocks on the completion, and the vast majority of
implementations is software only.