PSA: allow the configuration to favor HMAC_DRBG
Allow the user to configure PSA to use HMAC_DRBG even if CTR_DRBG is
available, or to explicitly select the hash algorithm to use for
HMAC_DRBG, by setting MBEDTLS_PSA_HMAC_DRBG_MD_TYPE in config.h.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index c022a61..5755df3 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3635,6 +3635,20 @@
*/
//#define MBEDTLS_PARAM_FAILED( cond ) assert( cond )
+/* PSA options */
+/** \def MBEDTLS_PSA_HMAC_DRBG_MD_TYPE
+ *
+ * Use HMAC_DRBG with the specified hash algorithm for HMAC_DRBG for the
+ * PSA crypto subsystem.
+ *
+ * If this option is unset:
+ * - If CTR_DRBG is available, the PSA subsystem uses it rather than HMAC_DRBG.
+ * - Otherwise, the PSA subsystem uses one HMAC_DRBG with of
+ * #MBEDTLS_MD_SHA512 or #MBEDTLS_MD_SHA256 based on availability and
+ * on unspecified heuristics.
+ */
+//#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
+
/* SSL Cache options */
//#define MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT 86400 /**< 1 day */
//#define MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES 50 /**< Maximum entries in cache */
diff --git a/programs/test/query_config.c b/programs/test/query_config.c
index 05a953c..1fb7384 100644
--- a/programs/test/query_config.c
+++ b/programs/test/query_config.c
@@ -2616,6 +2616,14 @@
}
#endif /* MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO */
+#if defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE)
+ if( strcmp( "MBEDTLS_PSA_HMAC_DRBG_MD_TYPE", config ) == 0 )
+ {
+ MACRO_EXPANSION_TO_STR( MBEDTLS_PSA_HMAC_DRBG_MD_TYPE );
+ return( 0 );
+ }
+#endif /* MBEDTLS_PSA_HMAC_DRBG_MD_TYPE */
+
#if defined(MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT)
if( strcmp( "MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT", config ) == 0 )
{
