From a30afe2216748997a1f184e16ddd1faf66f802b5 Mon Sep 17 00:00:00 2001
From: Minos Galanakis <minos.galanakis@arm.com>
Date: Wed, 15 Feb 2023 15:36:29 +0000
Subject: [PATCH] ecp_curves: Minor refactoring.

This patch introduces the following changes:
* Documentation for `mbedtls_ecp_modulus_setup()`
  moved to `ecp_invasive.h`.
* Added invalid modulus selector `MBEDTLS_ECP_MOD_NONE`.
* Adjusted negative tests to use invalid selectors.
* Reworded documentation.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
---
 include/mbedtls/ecp.h            |  5 +++--
 library/ecp_curves.c             | 18 +-----------------
 library/ecp_invasive.h           | 17 +++++++++++++++++
 tests/suites/test_suite_ecp.data |  4 ++--
 4 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 20b663e79..83d5b6ae6 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -142,10 +142,11 @@ typedef enum {
 } mbedtls_ecp_curve_type;
 
 /*
- * Curve moduli types
+ * Curve modulus types
  */
 typedef enum {
-    MBEDTLS_ECP_MOD_COORDINATE = 0,
+    MBEDTLS_ECP_MOD_NONE = 0,
+    MBEDTLS_ECP_MOD_COORDINATE,
     MBEDTLS_ECP_MOD_SCALAR
 } mbedtls_ecp_modulus_type;
 
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index d4d8c089e..b352e7633 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -5535,22 +5535,6 @@ static int ecp_mod_p256k1(mbedtls_mpi *N)
 #endif /* MBEDTLS_ECP_DP_SECP256K1_ENABLED */
 
 #if defined(MBEDTLS_TEST_HOOKS)
-
-/** Initialise a modulus with hard-coded const curve data.
- *
- * \param[out] N    The address of the modulus structure to populate.
- *                  Must be initialized.
- * \param[in] id    The mbedtls_ecp_group_id for which to initialise the modulus.
- * \param[in] ctype The mbedtls_ecp_curve_type identifier for a coordinate modulus (P)
- *                  or a scalar modulus (N).
- *
- * \return          \c 0 if successful.
- * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the given MPIs do not
- *                  have the correct number of limbs.
- *
- * \note            The caller is responsible for the \p N moduli lifecycle.
- *
- */
 MBEDTLS_STATIC_TESTABLE
 int mbedtls_ecp_modulus_setup(mbedtls_mpi_mod_modulus *N,
                               const mbedtls_ecp_group_id id,
@@ -5728,7 +5712,7 @@ int mbedtls_ecp_modulus_setup(mbedtls_mpi_mod_modulus *N,
 
     if (mbedtls_mpi_mod_modulus_setup(N, p, p_limbs,
                                       MBEDTLS_MPI_MOD_REP_MONTGOMERY)) {
-        return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+        return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     }
     return 0;
 }
diff --git a/library/ecp_invasive.h b/library/ecp_invasive.h
index 10aa34bb1..aba7cca1c 100644
--- a/library/ecp_invasive.h
+++ b/library/ecp_invasive.h
@@ -118,6 +118,23 @@ int mbedtls_ecp_mod_p521_raw(mbedtls_mpi_uint *X, size_t X_limbs);
 
 #endif /* MBEDTLS_ECP_DP_SECP521R1_ENABLED */
 
+/** Initialise a modulus with hard-coded const curve data.
+ *
+ * \note            The caller is responsible for the \p N modulus' memory.
+ *                  mbedtls_mpi_mod_modulus_free(&N) should be invoked at the
+ *                  end of its lifecycle.
+ *
+ * \param[in,out] N The address of the modulus structure to populate.
+ *                  Must be initialized.
+ * \param[in] id    The mbedtls_ecp_group_id for which to initialise the modulus.
+ * \param[in] ctype The mbedtls_ecp_curve_type identifier for a coordinate modulus (P)
+ *                  or a scalar modulus (N).
+ *
+ * \return          \c 0 if successful.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the given MPIs do not
+ *                  have the correct number of limbs.
+ *
+ */
 MBEDTLS_STATIC_TESTABLE
 int mbedtls_ecp_modulus_setup(mbedtls_mpi_mod_modulus *N,
                               const mbedtls_ecp_group_id id,
diff --git a/tests/suites/test_suite_ecp.data b/tests/suites/test_suite_ecp.data
index 8d838984b..3fbad92a5 100644
--- a/tests/suites/test_suite_ecp.data
+++ b/tests/suites/test_suite_ecp.data
@@ -1145,8 +1145,8 @@ ecp_mod_setup:"0000000000000003fffffffffffffffffffffffffffffffffffffffffffffffff
 
 ecp_setup_negative_test #27 Invalid Moduli Type
 depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
-ecp_mod_setup:"fffffffffffffffffffffffe26f2fc17f69466a74defd8d":MBEDTLS_ECP_DP_CURVE448:MBEDTLS_ECP_MOD_SCALAR+1:MBEDTLS_ERR_ECP_BAD_INPUT_DATA
+ecp_mod_setup:"fffffffffffffffffffffffe26f2fc17f69466a74defd8d":MBEDTLS_ECP_DP_CURVE448:MBEDTLS_ECP_MOD_NONE:MBEDTLS_ERR_ECP_BAD_INPUT_DATA
 
 ecp_setup_negative_test #28 Invalid Curve Type
 depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
-ecp_mod_setup:"fffffffffffffffffffffffe26f2fc17f69466a74defd8d":MBEDTLS_ECP_DP_CURVE448+1:MBEDTLS_ECP_MOD_SCALAR:MBEDTLS_ERR_ECP_BAD_INPUT_DATA
+ecp_mod_setup:"fffffffffffffffffffffffe26f2fc17f69466a74defd8d":MBEDTLS_ECP_DP_NONE:MBEDTLS_ECP_MOD_SCALAR:MBEDTLS_ERR_ECP_BAD_INPUT_DATA