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https://github.com/yuzu-emu/mbedtls.git
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hmac_drbg: make no reseeding behaviour explicit
Add a flag to the hmac_drbg context that will signal that reseeding is not required. Change tests and one ecdsa call to not use reseeding, as was the previous case. Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
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@ -77,6 +77,9 @@
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#define MBEDTLS_HMAC_DRBG_PR_OFF 0x55555555 /**< No prediction resistance */
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#define MBEDTLS_HMAC_DRBG_PR_ON 0x2AAAAAAA /**< Prediction resistance enabled */
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#define MBEDTLS_HMAC_DRBG_RESEED 0x78547854 /**< Default environment, reseeding enabled */
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#define MBEDTLS_HMAC_DRBG_NO_RESEED 0x07AB87F0 /**< Reseeding disabled, no f_entropy required */
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#ifdef __cplusplus
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extern "C" {
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#endif
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@ -91,7 +94,7 @@ typedef struct mbedtls_hmac_drbg_context
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mbedtls_md_context_t md_ctx; /*!< HMAC context (inc. K) */
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unsigned char V[MBEDTLS_MD_MAX_SIZE]; /*!< V in the spec */
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int reseed_counter; /*!< reseed counter */
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int reseed_flag; /*!< disables reseeding if set to MBEDTLS_HMAC_DRBG_NO_RESEED */
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/* Administrative state */
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size_t entropy_len; /*!< entropy bytes grabbed on each (re)seed */
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int prediction_resistance; /*!< enable prediction resistance (Automatic
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@ -220,6 +223,20 @@ int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
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void mbedtls_hmac_drbg_set_prediction_resistance( mbedtls_hmac_drbg_context *ctx,
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int resistance );
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/**
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* \brief This function turns reseeding on or off.
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* Default value is on.
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*
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* \note If set to MBEDTLS_HMAC_DRBG_NO_RESEED, this function
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* disables reseeding, providing a no_reseed environment.
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* f_entropy can then be null.
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*
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* \param ctx The HMAC_DRBG context.
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* \param reseed_flag #MBEDTLS_HMAC_DRBG_NO_RESEED or #MBEDTLS_HMAC_DRBG_RESEED
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*/
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void mbedtls_hmac_drbg_set_reseeding( mbedtls_hmac_drbg_context *ctx,
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int reseed_flag );
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/**
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* \brief This function sets the amount of entropy grabbed on each
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* seed or reseed.
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@ -482,6 +482,7 @@ sign:
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mbedtls_hmac_drbg_context rng_ctx_blind;
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mbedtls_hmac_drbg_init( &rng_ctx_blind );
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mbedtls_hmac_drbg_set_reseeding( &rng_ctx_blind, MBEDTLS_HMAC_DRBG_NO_RESEED );
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p_rng_blind_det = &rng_ctx_blind;
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mbedtls_hmac_drbg_seed_buf( p_rng_blind_det, md_info,
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@ -509,6 +510,7 @@ sign:
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* a valid ECDSA signature.
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*/
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p_rng_blind_det = p_rng;
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mbedtls_hmac_drbg_set_reseeding( p_rng_blind_det, MBEDTLS_HMAC_DRBG_NO_RESEED );
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#endif /* MBEDTLS_ECP_RESTARTABLE */
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/*
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@ -63,6 +63,7 @@ void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx )
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memset( ctx, 0, sizeof( mbedtls_hmac_drbg_context ) );
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ctx->prediction_resistance = MBEDTLS_HMAC_DRBG_PR_OFF;
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ctx->reseed_flag = MBEDTLS_HMAC_DRBG_RESEED;
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#if defined(MBEDTLS_THREADING_C)
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mbedtls_mutex_init( &ctx->mutex );
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#endif
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@ -388,6 +389,15 @@ void mbedtls_hmac_drbg_set_prediction_resistance( mbedtls_hmac_drbg_context *ctx
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ctx->prediction_resistance = resistance;
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}
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/*
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* Set the reseeding flag
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*/
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void mbedtls_hmac_drbg_set_reseeding( mbedtls_hmac_drbg_context *ctx,
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int reseed_flag )
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{
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ctx->reseed_flag = reseed_flag;
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}
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/*
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* Set entropy length grabbed for seeding
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*/
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@ -434,14 +444,20 @@ int mbedtls_hmac_drbg_random_with_add( void *p_rng,
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return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG );
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/* 1. (aka VII and IX) Check reseed counter and PR */
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if( ctx->f_entropy != NULL && /* For no-reseeding instances */
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( ctx->prediction_resistance == MBEDTLS_HMAC_DRBG_PR_ON ||
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ctx->reseed_counter > ctx->reseed_interval ) )
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if( ctx->reseed_flag != MBEDTLS_HMAC_DRBG_NO_RESEED &&
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( ctx->prediction_resistance == MBEDTLS_HMAC_DRBG_PR_ON ||
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ctx->reseed_counter > ctx->reseed_interval ) )
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{
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if( ( ret = mbedtls_hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )
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return( ret );
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add_len = 0; /* VII.4 */
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if( ctx->f_entropy == NULL )
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{
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return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED );
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}
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else
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{
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if( ( ret = mbedtls_hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )
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return( ret );
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add_len = 0; /* VII.4 */
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}
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}
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/* 2. Use additional data if any */
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@ -149,6 +149,7 @@ void hmac_drbg_buf( int md_alg )
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TEST_ASSERT( mbedtls_hmac_drbg_seed_buf( &ctx, md_info, buf, sizeof( buf ) ) == 0 );
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/* Make sure it never tries to reseed (would segfault otherwise) */
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mbedtls_hmac_drbg_set_reseeding( &ctx, MBEDTLS_HMAC_DRBG_NO_RESEED );
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mbedtls_hmac_drbg_set_reseed_interval( &ctx, 3 );
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mbedtls_hmac_drbg_set_prediction_resistance( &ctx, MBEDTLS_HMAC_DRBG_PR_ON );
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@ -172,7 +173,7 @@ void hmac_drbg_no_reseed( int md_alg, data_t * entropy,
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mbedtls_hmac_drbg_context ctx;
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mbedtls_hmac_drbg_init( &ctx );
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mbedtls_hmac_drbg_set_reseeding( &ctx, MBEDTLS_HMAC_DRBG_NO_RESEED );
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p_entropy.p = entropy->x;
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p_entropy.len = entropy->len;
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@ -219,6 +220,7 @@ void hmac_drbg_nopr( int md_alg, data_t * entropy, data_t * custom,
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mbedtls_hmac_drbg_context ctx;
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mbedtls_hmac_drbg_init( &ctx );
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mbedtls_hmac_drbg_set_reseeding( &ctx, MBEDTLS_HMAC_DRBG_NO_RESEED );
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p_entropy.p = entropy->x;
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p_entropy.len = entropy->len;
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