From 2566578a6feb9d9e39da41326afe8ed6022db3c5 Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Wed, 5 Nov 2008 12:13:14 +0800 Subject: 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 Signed-off-by: Jarod Wilson Signed-off-by: Herbert Xu --- crypto/ansi_cprng.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'crypto/ansi_cprng.c') diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c index 72db0fd763cc..486aa93646f7 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, } } }; -- cgit v1.2.3 From aa1a85dbd1d3265ca36f684026fe7689b7836bed Mon Sep 17 00:00:00 2001 From: Jarod Wilson Date: Thu, 13 Nov 2008 22:03:20 +0800 Subject: crypto: ansi_cprng - Avoid incorrect extra call to _get_more_prng_bytes While working with some FIPS RNGVS test vectors yesterday, I discovered a little bug in the way the ansi_cprng code works right now. For example, the following test vector (complete with expected result) from http://csrc.nist.gov/groups/STM/cavp/documents/rng/RNGVS.pdf ... Key = f3b1666d13607242ed061cabb8d46202 DT = e6b3be782a23fa62d71d4afbb0e922fc V = f0000000000000000000000000000000 R = 88dda456302423e5f69da57e7b95c73a ...when run through ansi_cprng, yields an incorrect R value of e2afe0d794120103d6e86a2b503bdfaa. If I load up ansi_cprng w/dbg=1 though, it was fairly obvious what was going wrong: ----8<---- getting 16 random bytes for context ffff810033fb2b10 Calling _get_more_prng_bytes for context ffff810033fb2b10 Input DT: 00000000: e6 b3 be 78 2a 23 fa 62 d7 1d 4a fb b0 e9 22 fc Input I: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Input V: 00000000: f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 tmp stage 0: 00000000: e6 b3 be 78 2a 23 fa 62 d7 1d 4a fb b0 e9 22 fc tmp stage 1: 00000000: f4 8e cb 25 94 3e 8c 31 d6 14 cd 8a 23 f1 3f 84 tmp stage 2: 00000000: 8c 53 6f 73 a4 1a af d4 20 89 68 f4 58 64 f8 be Returning new block for context ffff810033fb2b10 Output DT: 00000000: e7 b3 be 78 2a 23 fa 62 d7 1d 4a fb b0 e9 22 fc Output I: 00000000: 04 8e cb 25 94 3e 8c 31 d6 14 cd 8a 23 f1 3f 84 Output V: 00000000: 48 89 3b 71 bc e4 00 b6 5e 21 ba 37 8a 0a d5 70 New Random Data: 00000000: 88 dd a4 56 30 24 23 e5 f6 9d a5 7e 7b 95 c7 3a Calling _get_more_prng_bytes for context ffff810033fb2b10 Input DT: 00000000: e7 b3 be 78 2a 23 fa 62 d7 1d 4a fb b0 e9 22 fc Input I: 00000000: 04 8e cb 25 94 3e 8c 31 d6 14 cd 8a 23 f1 3f 84 Input V: 00000000: 48 89 3b 71 bc e4 00 b6 5e 21 ba 37 8a 0a d5 70 tmp stage 0: 00000000: e7 b3 be 78 2a 23 fa 62 d7 1d 4a fb b0 e9 22 fc tmp stage 1: 00000000: 80 6b 3a 8c 23 ae 8f 53 be 71 4c 16 fc 13 b2 ea tmp stage 2: 00000000: 2a 4d e1 2a 0b 58 8e e6 36 b8 9c 0a 26 22 b8 30 Returning new block for context ffff810033fb2b10 Output DT: 00000000: e8 b3 be 78 2a 23 fa 62 d7 1d 4a fb b0 e9 22 fc Output I: 00000000: c8 e2 01 fd 9f 4a 8f e5 e0 50 f6 21 76 19 67 9a Output V: 00000000: ba 98 e3 75 c0 1b 81 8d 03 d6 f8 e2 0c c6 54 4b New Random Data: 00000000: e2 af e0 d7 94 12 01 03 d6 e8 6a 2b 50 3b df aa returning 16 from get_prng_bytes in context ffff810033fb2b10 ----8<---- The expected result is there, in the first "New Random Data", but we're incorrectly making a second call to _get_more_prng_bytes, due to some checks that are slightly off, which resulted in our original bytes never being returned anywhere. One approach to fixing this would be to alter some byte_count checks in get_prng_bytes, but it would mean the last DEFAULT_BLK_SZ bytes would be copied a byte at a time, rather than in a single memcpy, so a slightly more involved, equally functional, and ultimately more efficient way of fixing this was suggested to me by Neil, which I'm submitting here. All of the RNGVS ANSI X9.31 AES128 VST test vectors I've passed through ansi_cprng are now returning the expected results with this change. Signed-off-by: Jarod Wilson Acked-by: Neil Horman Signed-off-by: Herbert Xu --- crypto/ansi_cprng.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) (limited to 'crypto/ansi_cprng.c') diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c index 486aa93646f7..1b3b1da1fd35 100644 --- a/crypto/ansi_cprng.c +++ b/crypto/ansi_cprng.c @@ -223,9 +223,10 @@ remainder: } /* - * Copy up to the next whole block size + * Copy any data less than an entire block */ if (byte_count < DEFAULT_BLK_SZ) { +empty_rbuf: for (; ctx->rand_data_valid < DEFAULT_BLK_SZ; ctx->rand_data_valid++) { *ptr = ctx->rand_data[ctx->rand_data_valid]; @@ -240,18 +241,22 @@ remainder: * Now copy whole blocks */ for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) { - if (_get_more_prng_bytes(ctx) < 0) { - memset(buf, 0, nbytes); - err = -EINVAL; - goto done; + if (ctx->rand_data_valid == DEFAULT_BLK_SZ) { + if (_get_more_prng_bytes(ctx) < 0) { + memset(buf, 0, nbytes); + err = -EINVAL; + goto done; + } } + if (ctx->rand_data_valid > 0) + goto empty_rbuf; memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ); ctx->rand_data_valid += DEFAULT_BLK_SZ; ptr += DEFAULT_BLK_SZ; } /* - * Now copy any extra partial data + * Now go back and get any remaining partial block */ if (byte_count) goto remainder; -- cgit v1.2.3 From 09fbf7c0f24176ef3b450c590f220ed8033dd2c3 Mon Sep 17 00:00:00 2001 From: Jarod Wilson Date: Mon, 24 Nov 2008 21:20:13 +0800 Subject: 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 Acked-by: Neil Horman Signed-off-by: Herbert Xu --- crypto/ansi_cprng.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'crypto/ansi_cprng.c') 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; -- cgit v1.2.3