Ignore domain parameters in RSA key generation

Remove the ability to select a custom public exponent via domain parameters
in RSA key generation. The only way to select a custom public exponent is
now to pass custom production parameters to psa_generate_key_ext().

A subsequent commit will remove domain parameters altogether from the API,
thus this commit does not bother to update the documentation.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/psa_crypto.c

@@ -7576,11 +7576,8 @@ psa_status_t psa_generate_key_internal(
          * that mbedtls_psa_rsa_generate_key() gets e via a new
          * parameter instead. */
         psa_key_attributes_t override_attributes = *attributes;
-        if (params_data_length != 0) {
-            override_attributes.domain_parameters_size = params_data_length;
-            override_attributes.domain_parameters = (uint8_t *) &params->data;
-        }
         return mbedtls_psa_rsa_generate_key(&override_attributes,
+                                            params, params_data_length,
                                             key_buffer,
                                             key_buffer_size,
                                             key_buffer_length);

library/psa_crypto_rsa.c

@@ -223,11 +223,6 @@ static psa_status_t psa_rsa_read_exponent(const uint8_t *domain_parameters,
     size_t i;
     uint32_t acc = 0;
 
-    if (domain_parameters_size == 0) {
-        *exponent = 65537;
-        return PSA_SUCCESS;
-    }
-
     /* Mbed TLS encodes the public exponent as an int. For simplicity, only
      * support values that fit in a 32-bit integer, which is larger than
      * int on just about every platform anyway. */
@@ -246,19 +241,21 @@ static psa_status_t psa_rsa_read_exponent(const uint8_t *domain_parameters,
 
 psa_status_t mbedtls_psa_rsa_generate_key(
     const psa_key_attributes_t *attributes,
+    const psa_key_production_parameters_t *params, size_t params_data_length,
     uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length)
 {
     psa_status_t status;
     mbedtls_rsa_context rsa;
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    int exponent;
+    int exponent = 65537;
 
-    status = psa_rsa_read_exponent(attributes->domain_parameters,
+    if (params_data_length != 0) {
-                                   attributes->domain_parameters_size,
+        status = psa_rsa_read_exponent(params->data, params_data_length,
                                        &exponent);
         if (status != PSA_SUCCESS) {
             return status;
         }
+    }
 
     mbedtls_rsa_init(&rsa);
     ret = mbedtls_rsa_gen_key(&rsa,

library/psa_crypto_rsa.h

@@ -109,6 +109,15 @@ psa_status_t mbedtls_psa_rsa_export_public_key(
  *       entry point.
  *
  * \param[in]  attributes         The attributes for the RSA key to generate.
+ * \param[in]  params             Production parameters for the key
+ *                                generation. This function only uses
+ *                                `params->data`,
+ *                                which contains the public exponent.
+ *                                This can be a null pointer if
+ *                                \c params_data_length is 0.
+ * \param params_data_length      Length of `params->data` in bytes.
+ *                                This can be 0, in which case the
+ *                                public exponent will be 65537.
  * \param[out] key_buffer         Buffer where the key data is to be written.
  * \param[in]  key_buffer_size    Size of \p key_buffer in bytes.
  * \param[out] key_buffer_length  On success, the number of bytes written in
@@ -123,6 +132,7 @@ psa_status_t mbedtls_psa_rsa_export_public_key(
  */
 psa_status_t mbedtls_psa_rsa_generate_key(
     const psa_key_attributes_t *attributes,
+    const psa_key_production_parameters_t *params, size_t params_data_length,
     uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length);
 
 /** Sign an already-calculated hash with an RSA private key.

tests/src/drivers/test_driver_key_management.c

@@ -225,10 +225,13 @@ psa_status_t mbedtls_test_transparent_generate_key(
         defined(LIBTESTDRIVER1_MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR_GENERATE)
         return libtestdriver1_mbedtls_psa_rsa_generate_key(
             (const libtestdriver1_psa_key_attributes_t *) attributes,
+            NULL, 0, /* We don't support custom e in the test driver yet */
             key, key_size, key_length);
 #elif defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR_GENERATE)
         return mbedtls_psa_rsa_generate_key(
-            attributes, key, key_size, key_length);
+            attributes,
+            NULL, 0, /* We don't support custom e in the test driver yet */
+            key, key_size, key_length);
 #endif
     } else if (PSA_KEY_TYPE_IS_DH(psa_get_key_type(attributes))
                && PSA_KEY_TYPE_IS_KEY_PAIR(psa_get_key_type(attributes))) {

tests/suites/test_suite_psa_crypto.data

@@ -7431,24 +7431,6 @@ PSA generate key: ECC, Curve448, good
 depends_on:PSA_WANT_ALG_ECDH:PSA_WANT_KEY_TYPE_ECC_KEY_PAIR_GENERATE:PSA_WANT_ECC_MONTGOMERY_448
 generate_key:PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_MONTGOMERY):448:PSA_KEY_USAGE_EXPORT | PSA_KEY_USAGE_DERIVE:PSA_ALG_ECDH:PSA_SUCCESS:0
 
-PSA generate key: RSA, domain parameters: default e
-generate_key_rsa:PSA_VENDOR_RSA_GENERATE_MIN_KEY_BITS:"":PSA_SUCCESS
-
-PSA generate key: RSA, domain parameters: e=3
-generate_key_rsa:PSA_VENDOR_RSA_GENERATE_MIN_KEY_BITS:"03":PSA_SUCCESS
-
-PSA generate key: RSA, domain parameters: e=65537
-generate_key_rsa:PSA_VENDOR_RSA_GENERATE_MIN_KEY_BITS:"010001":PSA_SUCCESS
-
-PSA generate key: RSA, domain parameters: e=513
-generate_key_rsa:PSA_VENDOR_RSA_GENERATE_MIN_KEY_BITS:"0201":PSA_SUCCESS
-
-PSA generate key: RSA, domain parameters: e=1
-generate_key_rsa:PSA_VENDOR_RSA_GENERATE_MIN_KEY_BITS:"01":PSA_ERROR_INVALID_ARGUMENT
-
-PSA generate key: RSA, domain parameters: e=2
-generate_key_rsa:PSA_VENDOR_RSA_GENERATE_MIN_KEY_BITS:"02":PSA_ERROR_INVALID_ARGUMENT
-
 PSA generate key: FFDH, 2048 bits, good
 depends_on:PSA_WANT_ALG_FFDH:PSA_WANT_KEY_TYPE_DH_KEY_PAIR_GENERATE:PSA_WANT_DH_RFC7919_2048
 generate_key:PSA_KEY_TYPE_DH_KEY_PAIR(PSA_DH_FAMILY_RFC7919):2048:PSA_KEY_USAGE_EXPORT:PSA_ALG_FFDH:PSA_SUCCESS:0

tests/suites/test_suite_psa_crypto.function

@@ -9840,88 +9840,6 @@ exit:
 }
 /* END_CASE */
 
-/* BEGIN_CASE depends_on:PSA_WANT_KEY_TYPE_RSA_KEY_PAIR_GENERATE:PSA_WANT_ALG_RSA_PKCS1V15_CRYPT:PSA_WANT_ALG_RSA_PKCS1V15_SIGN */
-void generate_key_rsa(int bits_arg,
-                      data_t *e_arg,
-                      int expected_status_arg)
-{
-    mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
-    psa_key_type_t type = PSA_KEY_TYPE_RSA_KEY_PAIR;
-    size_t bits = bits_arg;
-    psa_key_usage_t usage = PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT;
-    psa_algorithm_t alg = PSA_ALG_RSA_PKCS1V15_SIGN_RAW;
-    psa_status_t expected_status = expected_status_arg;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    uint8_t *e_read_buffer = NULL;
-    int is_default_public_exponent = 0;
-    size_t e_read_size = PSA_KEY_DOMAIN_PARAMETERS_SIZE(type, bits);
-    size_t e_read_length = SIZE_MAX;
-
-    if (e_arg->len == 0 ||
-        (e_arg->len == 3 &&
-         e_arg->x[0] == 1 && e_arg->x[1] == 0 && e_arg->x[2] == 1)) {
-        is_default_public_exponent = 1;
-        e_read_size = 0;
-    }
-    TEST_CALLOC(e_read_buffer, e_read_size);
-
-    PSA_ASSERT(psa_crypto_init());
-
-    psa_set_key_usage_flags(&attributes, usage);
-    psa_set_key_algorithm(&attributes, alg);
-    PSA_ASSERT(psa_set_key_domain_parameters(&attributes, type,
-                                             e_arg->x, e_arg->len));
-    psa_set_key_bits(&attributes, bits);
-
-    /* Generate a key */
-    TEST_EQUAL(psa_generate_key(&attributes, &key), expected_status);
-    if (expected_status != PSA_SUCCESS) {
-        goto exit;
-    }
-
-    /* Test the key information */
-    PSA_ASSERT(psa_get_key_attributes(key, &attributes));
-    TEST_EQUAL(psa_get_key_type(&attributes), type);
-    TEST_EQUAL(psa_get_key_bits(&attributes), bits);
-    psa_status_t status = psa_get_key_domain_parameters(&attributes,
-                                                        e_read_buffer, e_read_size,
-                                                        &e_read_length);
-
-
-#if (defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR_IMPORT) && \
-    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR_EXPORT)) || \
-    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
-    if (is_default_public_exponent) {
-        TEST_EQUAL(e_read_length, 0);
-    } else {
-        TEST_EQUAL(status, PSA_SUCCESS);
-        TEST_MEMORY_COMPARE(e_read_buffer, e_read_length, e_arg->x, e_arg->len);
-    }
-#else
-    (void) is_default_public_exponent;
-    TEST_EQUAL(status, PSA_ERROR_NOT_SUPPORTED);
-#endif
-
-    /* Do something with the key according to its type and permitted usage. */
-    if (!mbedtls_test_psa_exercise_key(key, usage, alg)) {
-        goto exit;
-    }
-
-    TEST_ASSERT(rsa_test_e(key, bits, e_arg));
-
-exit:
-    /*
-     * Key attributes may have been returned by psa_get_key_attributes() or
-     * set by psa_set_key_domain_parameters() thus reset them as required.
-     */
-    psa_reset_key_attributes(&attributes);
-
-    psa_destroy_key(key);
-    PSA_DONE();
-    mbedtls_free(e_read_buffer);
-}
-/* END_CASE */
-
 /* BEGIN_CASE */
 void generate_key_ext(int type_arg,
                       int bits_arg,