psa: let mbedtls_psa_get_random() always use psa_generate_random()
It means that mbedtls_psa_get_random() goes through the PSA interface
all the times. Fallbacks to CTR_DRBG or HMAC_DRBG are still possible,
but that depends on how the crypto provider is built.
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index 984f031..f79178d 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -23,42 +23,22 @@
#if defined(MBEDTLS_PSA_CRYPTO_C)
-/* Expose whatever RNG the PSA subsystem uses to applications using the
- * mbedtls_xxx API. The declarations and definitions here need to be
- * consistent with the implementation in library/psa_crypto_random_impl.h.
- * See that file for implementation documentation. */
-
-
-/* The type of a `f_rng` random generator function that many library functions
- * take.
- *
- * This type name is not part of the Mbed TLS stable API. It may be renamed
- * or moved without warning.
- */
-typedef int mbedtls_f_rng_t(void *p_rng, unsigned char *output, size_t output_size);
-
-#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
-
/** The random generator function for the PSA subsystem.
*
* This function is suitable as the `f_rng` random generator function
- * parameter of many `mbedtls_xxx` functions. Use #MBEDTLS_PSA_RANDOM_STATE
- * to obtain the \p p_rng parameter.
+ * parameter of many `mbedtls_xxx` functions.
*
* The implementation of this function depends on the configuration of the
* library.
*
- * \note Depending on the configuration, this may be a function or
- * a pointer to a function.
- *
* \note This function may only be used if the PSA crypto subsystem is active.
* This means that you must call psa_crypto_init() before any call to
* this function, and you must not call this function after calling
* mbedtls_psa_crypto_free().
*
- * \param p_rng The random generator context. This must be
- * #MBEDTLS_PSA_RANDOM_STATE. No other state is
- * supported.
+ * \param p_rng This parameter is only kept for backward compatibility
+ * reasons with legacy `f_rng` functions and it's ignored.
+ * Set to #MBEDTLS_PSA_RANDOM_STATE or NULL.
* \param output The buffer to fill. It must have room for
* \c output_size bytes.
* \param output_size The number of bytes to write to \p output.
@@ -80,32 +60,11 @@
/** The random generator state for the PSA subsystem.
*
- * This macro expands to an expression which is suitable as the `p_rng`
- * random generator state parameter of many `mbedtls_xxx` functions.
- * It must be used in combination with the random generator function
- * mbedtls_psa_get_random().
- *
- * The implementation of this macro depends on the configuration of the
- * library. Do not make any assumption on its nature.
+ * This macro always expands to NULL because the `p_rng` parameter is unused
+ * in mbedtls_psa_get_random(), but it's kept for interface's backward
+ * compatibility.
*/
-#define MBEDTLS_PSA_RANDOM_STATE NULL
-
-#else /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
-
-#if defined(MBEDTLS_CTR_DRBG_C)
-#include "mbedtls/ctr_drbg.h"
-typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
-static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_ctr_drbg_random;
-#elif defined(MBEDTLS_HMAC_DRBG_C)
-#include "mbedtls/hmac_drbg.h"
-typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
-static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_hmac_drbg_random;
-#endif
-extern mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state;
-
-#define MBEDTLS_PSA_RANDOM_STATE mbedtls_psa_random_state
-
-#endif /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
+#define MBEDTLS_PSA_RANDOM_STATE NULL
/** \defgroup psa_tls_helpers TLS helper functions
* @{