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_CTR_DRBG_RESEED_INTERVAL.
Signed-off-by: gacquroff <gavina352@gmail.com>
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 54843a7..023aac5 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -55,11 +55,17 @@
* See mbedtls_ctr_drbg_set_nonce_len(). */
ctx->reseed_counter = -1;
+ 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 )
@@ -70,6 +76,11 @@
#endif
mbedtls_aes_free( &ctx->aes_ctx );
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) );
+ ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+ ctx->reseed_counter = -1;
+#if defined(MBEDTLS_THREADING_C)
+ mbedtls_mutex_init( &ctx->mutex );
+#endif
}
void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx,
@@ -468,8 +479,6 @@
(size_t) ctx->reseed_counter :
good_nonce_len( ctx->entropy_len ) );
- ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
-
/* Initialize with an empty key. */
if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )