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>
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 <jarod@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 patch adds a random number generator interface as well as a
cryptographic pseudo-random number generator based on AES. It is
meant to be used in cases where a deterministic CPRNG is required.
One of the first applications will be as an input in the IPsec IV
generation process.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
