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authorJarod Wilson <jarod@redhat.com>2008-11-24 21:20:13 +0800
committerHerbert Xu <herbert@gondor.apana.org.au>2008-12-25 11:01:49 +1100
commit09fbf7c0f24176ef3b450c590f220ed8033dd2c3 (patch)
treeb4f6f918cc43ee50f459d4f95ef6a100cf43db83 /crypto
parent93027354d6e8a66a12dedb89d59b21cf7c2d35ed (diff)
downloadconfigs-09fbf7c0f24176ef3b450c590f220ed8033dd2c3.tar.gz
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.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 1b3b1da1fd3..0fac8ffc2fb 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;