RSA: Use hashlen as the hash input size as documented

Where hashlen was previously ignored when the hash length could be
inferred from an md_alg parameter, the two must now match.

Adapt the existing tests accordingly. Adapt the sample programs accordingly.

This commit does not add any negative testing.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_rsa.function b/tests/suites/test_suite_rsa.function
index 14b4afc..1bffc76 100644
--- a/tests/suites/test_suite_rsa.function
+++ b/tests/suites/test_suite_rsa.function
@@ -86,6 +86,7 @@
                              data_t * result_str, int result )
 {
     unsigned char hash_result[MBEDTLS_MD_MAX_SIZE];
+    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( digest );
     unsigned char output[256];
     mbedtls_rsa_context ctx;
     mbedtls_mpi N, P, Q, E;
@@ -111,13 +112,13 @@
     TEST_ASSERT( mbedtls_rsa_complete( &ctx ) == 0 );
     TEST_ASSERT( mbedtls_rsa_check_privkey( &ctx ) == 0 );
 
+    if( md_info != NULL )
+        TEST_ASSERT( mbedtls_md( md_info, message_str->x, message_str->len, hash_result ) == 0 );
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
-        TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
-
-    TEST_ASSERT( mbedtls_rsa_pkcs1_sign( &ctx, &mbedtls_test_rnd_pseudo_rand,
-                                         &rnd_info, digest, 0, hash_result,
-                                         output ) == result );
+    TEST_ASSERT( mbedtls_rsa_pkcs1_sign(
+                     &ctx, &mbedtls_test_rnd_pseudo_rand, &rnd_info,
+                     digest, mbedtls_md_get_size( md_info ), hash_result,
+                     output ) == result );
     if( result == 0 )
     {
 
@@ -139,8 +140,8 @@
                                data_t * result_str, int result )
 {
     unsigned char hash_result[MBEDTLS_MD_MAX_SIZE];
+    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( digest );
     mbedtls_rsa_context ctx;
-
     mbedtls_mpi N, E;
 
     mbedtls_mpi_init( &N ); mbedtls_mpi_init( &E );
@@ -155,11 +156,10 @@
     TEST_ASSERT( mbedtls_rsa_get_len( &ctx ) == (size_t) ( mod / 8 ) );
     TEST_ASSERT( mbedtls_rsa_check_pubkey( &ctx ) == 0 );
 
+    if( md_info != NULL )
+        TEST_ASSERT( mbedtls_md( md_info, message_str->x, message_str->len, hash_result ) == 0 );
 
-    if( mbedtls_md_info_from_type( digest ) != NULL )
-        TEST_ASSERT( mbedtls_md( mbedtls_md_info_from_type( digest ), message_str->x, message_str->len, hash_result ) == 0 );
-
-    TEST_ASSERT( mbedtls_rsa_pkcs1_verify( &ctx, digest, 0, hash_result, result_str->x ) == result );
+    TEST_ASSERT( mbedtls_rsa_pkcs1_verify( &ctx, digest, mbedtls_md_get_size( md_info ), hash_result, result_str->x ) == result );
 
 exit:
     mbedtls_mpi_free( &N ); mbedtls_mpi_free( &E );