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From: David Howells <dhowells@redhat.com>
To: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: dhowells@redhat.com, "Zaborowski,
	Andrew" <andrew.zaborowski@intel.com>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
Subject: Re: RSA/MPI handling issues and keyctl access to public key keyrings
Date: Wed, 11 May 2016 14:55:56 +0100	[thread overview]
Message-ID: <2114.1462974956@warthog.procyon.org.uk> (raw)
In-Reply-To: <268bb9cd-08ca-aae9-5b12-91d8c0195bc1@intel.com>

Tadeusz Struk <tadeusz.struk@intel.com> wrote:

> >  (2) rsa-pkcs1pad needs to indicate what the maximum content size is, given
> >      the minimum possible padding for the specified hash type (ie. a
> >      particular OID).
> 
> The user needs to use crypto_akcipher_maxsize(tfm) to get the required buffer
> size for a given key.
> We do check if the buffer if big enough to accommodate padding and hash info.
> This is needed in sign and encrypt operations, and in both cases we check it,
> sign:
> https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/tree/crypto/rsa-pkcs1pad.c#n434
> and encrypt:
> https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/tree/crypto/rsa-pkcs1pad.c#n252

Can you supply a way to find out the reduced size from the padding?

David

  reply	other threads:[~2016-05-11 13:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <7781.1462785198@warthog.procyon.org.uk>
2016-05-09 22:56 ` RSA/MPI handling issues and keyctl access to public key keyrings Tadeusz Struk
2016-05-11 13:55   ` David Howells [this message]
2016-05-11 21:11     ` Tadeusz Struk

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