Support set *_drbg reseed interval before seed

mbedtls_ctr_drbg_set_reseed_interval() and
mbedtls_hmac_drbg_set_reseed_interval() can now be called before
their seed functions and the reseed_interval value will persist.
Previously it would be overwritten with the default value.

*_drbg_reseed_interval is now set in init() and free().

mbedtls_ctr_drbg_free() and mbedtls_hmac_drbg_free() now
reset the drbg context to the state immediately after init().

Tests:
- Added test to check that DRBG reseeds when reseed_counter
reaches reseed_interval, if reseed_interval set before seed
and reseed_interval is less than MBEDTLS_*_DRBG_RESEED_INTERVAL.

Signed-off-by: gacquroff <gavina352@gmail.com>
This commit is contained in:
Gavin Acquroff 2020-03-01 17:06:11 -08:00 committed by gacquroff
parent e98bbbeb06
commit 77cb30c3cb
6 changed files with 53 additions and 20 deletions

View file

@ -82,11 +82,17 @@ void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx )
{
memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) );
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &ctx->mutex );
#endif
}
/*
* This function resets CTR_DRBG context to the state immediately
* after initial call of mbedtls_ctr_drbg_init().
*/
void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
{
if( ctx == NULL )
@ -97,6 +103,10 @@ void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
#endif
mbedtls_aes_free( &ctx->aes_ctx );
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) );
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &ctx->mutex );
#endif
}
void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, int resistance )
@ -419,7 +429,6 @@ int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
if( ctx->entropy_len == 0 )
ctx->entropy_len = MBEDTLS_CTR_DRBG_ENTROPY_LEN;
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
/*
* Initialize with an empty key