Implement MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG
Implement support for MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG.
For test purposes, write an implementation that uses libc rand().
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/psa_crypto_random.h b/library/psa_crypto_random.h
index 95974d9..2e7f94d 100644
--- a/library/psa_crypto_random.h
+++ b/library/psa_crypto_random.h
@@ -22,6 +22,34 @@
#ifndef PSA_CRYPTO_RANDOM_H
#define PSA_CRYPTO_RANDOM_H
+#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
+
+#include <string.h>
+#include <mbedtls/entropy.h> // only for error codes
+#include <psa/crypto.h>
+
+typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t;
+
+static inline int mbedtls_psa_get_random( void *p_rng,
+ unsigned char *output,
+ size_t output_size )
+{
+ (void) p_rng;
+ psa_status_t status = psa_generate_random( output, output_size );
+ if( status == PSA_SUCCESS )
+ return( 0 );
+ else
+ return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
+}
+
+static inline void *mbedtls_psa_random_state( mbedtls_psa_random_context_t *rng )
+{
+ (void) rng;
+ return( NULL );
+}
+
+#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
+
/* Currently, the only supported RNG is Mbed TLS's CTR_DRBG seeded with
* mbedtls_entropy_func(). */
@@ -127,4 +155,6 @@
custom, len ) );
}
+#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
+
#endif /* PSA_CRYPTO_RANDOM_H */