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| author | Jarod Wilson <jarod@redhat.com> | 2008-11-24 21:20:13 +0800 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2008-12-25 11:01:49 +1100 |
| commit | 09fbf7c0f24176ef3b450c590f220ed8033dd2c3 (patch) | |
| tree | b4f6f918cc43ee50f459d4f95ef6a100cf43db83 /crypto | |
| parent | 93027354d6e8a66a12dedb89d59b21cf7c2d35ed (diff) | |
| download | linux-09fbf7c0f24176ef3b450c590f220ed8033dd2c3.tar.gz linux-09fbf7c0f24176ef3b450c590f220ed8033dd2c3.tar.bz2 linux-09fbf7c0f24176ef3b450c590f220ed8033dd2c3.zip | |
crypto: ansi_cprng - fix inverted DT increment routine
The ANSI X9.31 PRNG docs aren't particularly clear on how to increment DT,
but empirical testing shows we're incrementing from the wrong end. A 10,000
iteration Monte Carlo RNG test currently winds up not getting the expected
result.
From http://csrc.nist.gov/groups/STM/cavp/documents/rng/RNGVS.pdf :
# CAVS 4.3
# ANSI931 MCT
[X9.31]
[AES 128-Key]
COUNT = 0
Key = 9f5b51200bf334b5d82be8c37255c848
DT = 6376bbe52902ba3b67c925fa701f11ac
V = 572c8e76872647977e74fbddc49501d1
R = 48e9bd0d06ee18fbe45790d5c3fc9b73
Currently, we get 0dd08496c4f7178bfa70a2161a79459a after 10000 loops.
Inverting the DT increment routine results in us obtaining the expected result
of 48e9bd0d06ee18fbe45790d5c3fc9b73. Verified on both x86_64 and ppc64.
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/ansi_cprng.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c index 1b3b1da1fd35..0fac8ffc2fb7 100644 --- a/crypto/ansi_cprng.c +++ b/crypto/ansi_cprng.c @@ -161,7 +161,7 @@ static int _get_more_prng_bytes(struct prng_context *ctx) /* * Now update our DT value */ - for (i = 0; i < DEFAULT_BLK_SZ; i++) { + for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) { ctx->DT[i] += 1; if (ctx->DT[i] != 0) break; |