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Change RNG test to block oriented instead of request oriented, add option

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to test a "stuck" DRBG.
This commit is contained in:
Dr. Stephen Henson
2011-04-04 14:47:31 +00:00
parent a255e5bc98
commit ded1999702
8 changed files with 82 additions and 68 deletions
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102
fips/rand/fips_drbg_lib.c
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@@ -268,8 +268,7 @@ int FIPS_drbg_reseed(DRBG_CTX *dctx,
}
static int fips_drbg_generate_internal(DRBG_CTX *dctx,
unsigned char *out, size_t outlen,
int FIPS_drbg_generate(DRBG_CTX *dctx, unsigned char *out, size_t outlen,
int strength, int prediction_resistance,
const unsigned char *adin, size_t adinlen)
{
@@ -323,76 +322,13 @@ static int fips_drbg_generate_internal(DRBG_CTX *dctx,
if (r)
{
if (!(dctx->flags & DRBG_FLAG_NOERR))
FIPSerr(FIPS_F_FIPS_DRBG_GENERATE_INTERNAL, r);
FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, r);
return 0;
}
return 1;
}
/* external generate function: incorporates continuous RNG test if not
* in test mode.
*/
int FIPS_drbg_generate(DRBG_CTX *dctx,
unsigned char *out, size_t outlen,
int strength, int prediction_resistance,
const unsigned char *adin, size_t adinlen)
{
unsigned char tmp[16], *pout;
size_t poutlen;
/* If test mode don't run continuous RNG test */
if (dctx->flags & DRBG_FLAG_TEST)
{
return fips_drbg_generate_internal(dctx, out, outlen,
strength,
prediction_resistance,
adin, adinlen);
}
/* If this is the first call generate block and save buffer */
if (!dctx->lb_valid)
{
if (!fips_drbg_generate_internal(dctx, dctx->lb, 16,
strength, prediction_resistance,
adin, adinlen))
return 0;
dctx->lb_valid = 1;
}
/* If request less that 16 bytes request 16 in temp buffer */
if (outlen < 16)
{
pout = tmp;
poutlen = 16;
}
else
{
pout = out;
poutlen = outlen;
}
/* Generate data */
if (!fips_drbg_generate_internal(dctx, pout, poutlen,
strength, prediction_resistance,
adin, adinlen))
return 0;
/* Compare to last block for continuous PRNG test */
if (!memcmp(pout, dctx->lb, 16))
{
FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, FIPS_R_DRBG_STUCK);
return 0;
}
/* Update last block */
memcpy(dctx->lb, pout, 16);
/* Copy to output buffer if needed */
if (outlen < 16)
memcpy(out, pout, outlen);
return 1;
}
int FIPS_drbg_uninstantiate(DRBG_CTX *dctx)
{
int rv;
@@ -461,3 +397,37 @@ int FIPS_drbg_get_strength(DRBG_CTX *dctx)
{
return dctx->strength;
}
static int drbg_stick = 0;
void FIPS_drbg_stick(void)
{
drbg_stick = 1;
}
/* Continuous DRBG utility function */
int drbg_cprng_test(DRBG_CTX *dctx, const unsigned char *out)
{
/* No CPRNG in test mode */
if (dctx->flags & DRBG_FLAG_TEST)
return 1;
/* Check block is valid: should never happen */
if (dctx->lb_valid == 0)
{
FIPSerr(FIPS_F_DRBG_CPRNG_TEST, FIPS_R_INTERNAL_ERROR);
fips_set_selftest_fail();
return 0;
}
if (drbg_stick)
memcpy(dctx->lb, out, dctx->blocklength);
/* Check against last block: fail if match */
if (!memcmp(dctx->lb, out, dctx->blocklength))
{
FIPSerr(FIPS_F_DRBG_CPRNG_TEST, FIPS_R_DRBG_STUCK);
fips_set_selftest_fail();
return 0;
}
/* Save last block for next comparison */
memcpy(dctx->lb, out, dctx->blocklength);
return 1;
}