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From:   Kalyani Akula <kalyania@xilinx.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>
CC:     Stephan Mueller <smueller@chronox.de>,
        "keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Sarat Chand Savitala <saratcha@xilinx.com>
Subject: RE: [RFC PATCH 4/5] crypto: Adds user space interface for
 ALG_SET_KEY_TYPE
Thread-Topic: [RFC PATCH 4/5] crypto: Adds user space interface for
 ALG_SET_KEY_TYPE
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Date:   Thu, 11 Jul 2019 09:25:38 +0000
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Hi Herbert,

Paes driver is using key expansion algorithm to encrypt and decrypt the pla=
intext. HW capability of expanding the given plain key is checked based on =
the provide key length. Here the HW key is the expended version of plain ke=
y.

Xilinx AES hardware has a capability to take plain keys/encrypted keys ( th=
ese keys are user programmable but for security reasons they are not readab=
le. Only AES accelerator has read access to these keys) stored on chip ( in=
 eFuse/BBRAM etc, ) and used for AES encryption/decryption.
Xilinx software is giving the Customer, the flexibility to choose among the=
 different on-chip AES keys.
So, we chosen a way to add AES_SEL_HW_KEY option.

In Paes driver , The ALG_SET_KEY interface is used to distinguish between H=
W Vs SW expansion of plain key based on the key_len.=20

How about using same interface to distinguish between the User supplied key=
 Vs HW key selection based on key_len parameter.

Thanks
kalyani  =09

> -----Original Message-----
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Sent: Monday, June 10, 2019 12:05 PM
> To: Kalyani Akula <kalyania@xilinx.com>
> Cc: Stephan Mueller <smueller@chronox.de>; keyrings@vger.kernel.org;
> davem@davemloft.net; linux-crypto@vger.kernel.org; linux-
> kernel@vger.kernel.org; Sarat Chand Savitala <saratcha@xilinx.com>
> Subject: Re: [RFC PATCH 4/5] crypto: Adds user space interface for
> ALG_SET_KEY_TYPE
>=20
> On Mon, Jun 10, 2019 at 05:20:58AM +0000, Kalyani Akula wrote:
> > Ping!!
>=20
> We already have existing drivers supporting hardware keys.  Please check
> out how they're handling this.  You can grep for paes under drivers/crypt=
o.
>=20
> Cheers,
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au> Home Page:
> http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt