Expose mbedtls_psa_get_random()

Expose whatever RNG the PSA subsystem uses to applications using the
mbedtls_xxx API.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_random.function b/tests/suites/test_suite_random.function
index 744daf5..c532c8a 100644
--- a/tests/suites/test_suite_random.function
+++ b/tests/suites/test_suite_random.function
@@ -2,9 +2,12 @@
 
 /* Test random generation as a whole. */
 
+#include "mbedtls/bignum.h"
 #include "mbedtls/ctr_drbg.h"
+#include "mbedtls/ecdsa.h"
 #include "mbedtls/entropy.h"
 #include "mbedtls/hmac_drbg.h"
+#include "mbedtls/psa_util.h"
 #include "psa/crypto.h"
 
 /* How many bytes to generate in each test case for repeated generation.
@@ -95,6 +98,32 @@
 /* END_CASE */
 
 /* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_C:!MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
+void random_twice_with_psa_from_classic( )
+{
+    unsigned char output1[OUTPUT_SIZE];
+    unsigned char output2[OUTPUT_SIZE];
+
+    /* First round */
+    PSA_ASSERT( psa_crypto_init( ) );
+    TEST_EQUAL( 0, mbedtls_psa_get_random( MBEDTLS_PSA_RANDOM_STATE,
+                                           output1, sizeof( output1 ) ) );
+    PSA_DONE( );
+
+    /* Second round */
+    PSA_ASSERT( psa_crypto_init( ) );
+    TEST_EQUAL( 0, mbedtls_psa_get_random( MBEDTLS_PSA_RANDOM_STATE,
+                                           output2, sizeof( output2 ) ) );
+    PSA_DONE( );
+
+    /* The two rounds must generate different random data. */
+    TEST_ASSERT( memcmp( output1, output2, OUTPUT_SIZE ) != 0 );
+
+exit:
+    PSA_DONE( );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_C:!MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
 void random_twice_with_psa_from_psa( )
 {
     unsigned char output1[OUTPUT_SIZE];
@@ -117,3 +146,57 @@
     PSA_DONE( );
 }
 /* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_C */
+void mbedtls_psa_get_random_no_init( )
+{
+    unsigned char output[1];
+
+    TEST_ASSERT( mbedtls_psa_get_random( MBEDTLS_PSA_RANDOM_STATE,
+                                         output, sizeof( output ) ) != 0 );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_C */
+void mbedtls_psa_get_random_length( int n )
+{
+    unsigned char *output = NULL;
+
+    PSA_ASSERT( psa_crypto_init( ) );
+    ASSERT_ALLOC( output, n );
+
+    TEST_EQUAL( 0, mbedtls_psa_get_random( MBEDTLS_PSA_RANDOM_STATE,
+                                           output, n ) );
+exit:
+    mbedtls_free( output );
+    PSA_DONE( );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_C:MBEDTLS_ECDSA_C */
+void mbedtls_psa_get_random_ecdsa_sign( int curve )
+{
+    mbedtls_ecp_group grp;
+    mbedtls_mpi d, r, s;
+    unsigned char buf[] = "This is not a hash.";
+
+    mbedtls_ecp_group_init( &grp );
+    mbedtls_mpi_init( &d );
+    mbedtls_mpi_init( &r );
+    mbedtls_mpi_init( &s );
+
+    TEST_EQUAL( 0, mbedtls_mpi_lset( &d, 123456789 ) );
+    TEST_EQUAL( 0, mbedtls_ecp_group_load( &grp, curve ) );
+    PSA_ASSERT( psa_crypto_init( ) );
+    TEST_EQUAL( 0, mbedtls_ecdsa_sign( &grp, &r, &s, &d,
+                                       buf, sizeof( buf ),
+                                       mbedtls_psa_get_random,
+                                       MBEDTLS_PSA_RANDOM_STATE ) );
+exit:
+    mbedtls_mpi_free( &d );
+    mbedtls_mpi_free( &r );
+    mbedtls_mpi_free( &s );
+    mbedtls_ecp_group_free( &grp );
+    PSA_DONE( );
+}
+/* END_CASE */