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[rng] Record validity within DRBG state

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Treat an empty (zeroed) DRBG as invalid.  This ensures that a DRBG
that has not yet been instantiated (or that has been uninstantiated)
will refuse to attempt to generate random bits.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2012-02-20 21:24:30 +00:00
parent a99d5d5aca
commit c2668b61ea
2 changed files with 15 additions and 4 deletions
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17
src/crypto/drbg.c
View File

@ -151,6 +151,7 @@ int drbg_instantiate ( struct drbg_state *state, const void *personal,
* in-situ.) * in-situ.)
*/ */
state->reseed_required = 0; state->reseed_required = 0;
state->valid = 1;
/* 12. Return SUCCESS and state_handle. */ /* 12. Return SUCCESS and state_handle. */
return 0; return 0;
@ -187,9 +188,13 @@ int drbg_reseed ( struct drbg_state *state, const void *additional,
* If state_handle indicates an invalid or empty internal * If state_handle indicates an invalid or empty internal
* state, return an ERROR_FLAG. * state, return an ERROR_FLAG.
* *
* (Nothing to do since the memory holding the internal state * (Almost nothing to do since the memory holding the internal
* was passed in by the caller.) * state was passed in by the caller.)
*/ */
if ( ! state->valid ) {
DBGC ( state, "DRBG %p not valid\n", state );
return -EINVAL;
}
/* 2. If prediction_resistance_request is set, and /* 2. If prediction_resistance_request is set, and
* prediction_resistance_flag is not set, then return an * prediction_resistance_flag is not set, then return an
@ -273,9 +278,13 @@ int drbg_generate ( struct drbg_state *state, const void *additional,
* for the instantiation. If state_handle indicates an * for the instantiation. If state_handle indicates an
* invalid or empty internal state, then return an ERROR_FLAG. * invalid or empty internal state, then return an ERROR_FLAG.
* *
* (Nothing to do since the memory holding the internal state * (Almost nothing to do since the memory holding the internal
* was passed in by the caller.) * state was passed in by the caller.)
*/ */
if ( ! state->valid ) {
DBGC ( state, "DRBG %p not valid\n", state );
return -EINVAL;
}
/* 2. If requested_number_of_bits > /* 2. If requested_number_of_bits >
* max_number_of_bits_per_request, then return an * max_number_of_bits_per_request, then return an

2
src/include/ipxe/drbg.h
View File

@ -39,6 +39,8 @@ struct drbg_state {
struct hmac_drbg_state internal; struct hmac_drbg_state internal;
/** Reseed required flag */ /** Reseed required flag */
int reseed_required; int reseed_required;
/** State is valid */
int valid;
}; };
/** /**