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crypto: ansi_cprng - Allow resetting of DT value 

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.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Neil Horman 2008-11-05 12:13:14 +08:00 committed by Herbert Xu
parent 420a4b20c5
commit 2566578a6f
1 changed files with 13 additions and 3 deletions
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16
crypto/ansi_cprng.c
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@ -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,
}
}
};