From: Jarod Wilson Subject: Re: [PATCH] crypto: extend ansi_cprng to allow resetting of DT value Date: Tue, 4 Nov 2008 16:04:24 -0500 Message-ID: <200811041604.24895.jarod@redhat.com> References: <20081103212240.GB24888@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: herbert@gondor.apana.org.au, davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org To: Neil Horman Return-path: Received: from mx2.redhat.com ([66.187.237.31]:40932 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753585AbYKDVEk (ORCPT ); Tue, 4 Nov 2008 16:04:40 -0500 In-Reply-To: <20081103212240.GB24888@hmsreliant.think-freely.org> Content-Disposition: inline Sender: linux-crypto-owner@vger.kernel.org List-ID: On Monday 03 November 2008 16:22:40 Neil Horman wrote: > Hey all- > This is a patch that was sent to me by Jarod Wilson, marking off my > outstanding todo to allow the ansi cprng to set/reset the DT counter value > in a cprng instance. Currently crytpo_rng_reset accepts a seed byte array > which is interpreted by the ansi_cprng as a {V key} tuple. This patch > extends that tuple to now be {V key DT}, with DT an optional value during > reset. This patch also fixes a bug we noticed in which the offset of the > key area of the seed is started at DEFAULT_PRNG_KSZ rather than > DEFAULT_BLK_SZ as it should be. > > Regards > Neil > > Signed-off-by: Neil Horman Even better than my original version, since it lets providing a DT value be optional. Go ahead and slap this on there too: Signed-off-by: Jarod Wilson > ansi_cprng.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > > diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c > index 72db0fd..486aa93 100644 > --- a/crypto/ansi_cprng.c > +++ b/crypto/ansi_cprng.c > @@ -349,15 +349,25 @@ static int cprng_get_random(struct crypto_rng *tfm, > u8 *rdata, return get_prng_bytes(rdata, dlen, prng); > } > > +/* > + * This is the cprng_registered reset method the seed value is > + * interpreted as the tuple { V KEY DT} > + * V and KEY are required during reset, and DT is optional, detected > + * as being present by testing the length of the seed > + */ > static int cprng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int > slen) { > struct prng_context *prng = crypto_rng_ctx(tfm); > - u8 *key = seed + DEFAULT_PRNG_KSZ; > + u8 *key = seed + DEFAULT_BLK_SZ; > + u8 *dt = NULL; > > if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ) > return -EINVAL; > > - reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, NULL); > + if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ)) > + dt = key + DEFAULT_PRNG_KSZ; > + > + reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt); > > if (prng->flags & PRNG_NEED_RESET) > return -EINVAL; > @@ -379,7 +389,7 @@ static struct crypto_alg rng_alg = { > .rng = { > .rng_make_random = cprng_get_random, > .rng_reset = cprng_reset, > - .seedsize = DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ, > + .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ, > } > } > }; -- Jarod Wilson jarod@redhat.com