fix(hal): Make the ECDSA countermeasure dynamically applicable

This commit makes the ECDSA countermeasure dynamically applicable
    across different revisions of the ESP32H2 SoC.

components/esp_hw_support/Kconfig

@@ -346,18 +346,4 @@ menu "Hardware Settings"
             time point multiplication operations by changing the default ESP-IDF configurations.
             Performing constant time operations protect the ECC multiplication operations from timing attacks.
 
-    orsource "./port/$IDF_TARGET/Kconfig.dcdc"
-
-    orsource "./port/$IDF_TARGET/Kconfig.ldo"
-
-    # Invisible bringup bypass options for esp_hw_support component
-    config ESP_BRINGUP_BYPASS_CPU_CLK_SETTING
-        bool
-        default y if !SOC_CLK_TREE_SUPPORTED
-        default n
-        help
-            This option is only used for new chip bringup, when
-            clock support isn't done yet. So with this option,
-            we use xtal on FPGA as the clock source.
-
 endmenu

components/esp_system/port/cpu_start.c

@@ -249,7 +249,13 @@ static void start_other_core(void)
 #endif
 
 #if CONFIG_ESP_CRYPTO_FORCE_ECC_CONSTANT_TIME_POINT_MUL
-    if (!esp_efuse_read_field_bit(ESP_EFUSE_ECC_FORCE_CONST_TIME)) {
+    bool force_constant_time = true;
+#if CONFIG_IDF_TARGET_ESP32H2
+    if (!ESP_CHIP_REV_ABOVE(efuse_hal_chip_revision(), 102)) {
+        force_constant_time = false;
+    }
+#endif
+    if (!esp_efuse_read_field_bit(ESP_EFUSE_ECC_FORCE_CONST_TIME) && force_constant_time) {
         ESP_EARLY_LOGD(TAG, "Forcefully enabling ECC constant time operations");
         esp_err_t err = esp_efuse_write_field_bit(ESP_EFUSE_ECC_FORCE_CONST_TIME);
         if (err != ESP_OK) {

components/hal/Kconfig

@@ -105,7 +105,7 @@ menu "Hardware Abstraction Layer (HAL) and Low Level (LL)"
 
     config HAL_ECDSA_GEN_SIG_CM
         bool "Enable countermeasure for ECDSA signature generation"
-        depends on IDF_TARGET_ESP32H2 && ESP32H2_REV_MIN_FULL < 102
+        depends on IDF_TARGET_ESP32H2
         default n
         help
             Enable this option to apply the countermeasure for ECDSA signature operation

components/hal/ecdsa_hal.c

@@ -12,6 +12,7 @@
 #if CONFIG_HAL_ECDSA_GEN_SIG_CM
 #include "esp_fault.h"
 #include "esp_random.h"
+#include "soc/chip_revision.h"
 #endif
 
 #define ECDSA_HAL_P192_COMPONENT_LEN        24
@@ -108,7 +109,11 @@ void ecdsa_hal_gen_signature(ecdsa_hal_config_t *conf, const uint8_t *hash,
     configure_ecdsa_periph(conf);
 
 #if CONFIG_HAL_ECDSA_GEN_SIG_CM
-    ecdsa_hal_gen_signature_with_countermeasure(hash, r_out, s_out, len);
+    if (!ESP_CHIP_REV_ABOVE(efuse_hal_chip_revision(), 102)) {
+        ecdsa_hal_gen_signature_with_countermeasure(hash, r_out, s_out, len);
+    } else {
+        ecdsa_hal_gen_signature_inner(hash, r_out, s_out, len);
+    }
 #else /* CONFIG_HAL_ECDSA_GEN_SIG_CM */
     ecdsa_hal_gen_signature_inner(hash, r_out, s_out, len);
 #endif /* !CONFIG_HAL_ECDSA_GEN_SIG_CM */

components/hal/test_apps/ecc/CMakeLists.txt

@@ -2,6 +2,8 @@ cmake_minimum_required(VERSION 3.16)
 
 set(COMPONENTS main)
 
+set(EXTRA_COMPONENT_DIRS "$ENV{IDF_PATH}/tools/unit-test-app/components")
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 
+
 project(ecc_test)

components/hal/test_apps/ecc/main/CMakeLists.txt

@@ -2,5 +2,5 @@ set(srcs "app_main.c"
          "test_ecc.c")
 
 idf_component_register(SRCS ${srcs}
-                       REQUIRES unity
+                       REQUIRES unity test_utils
                        WHOLE_ARCHIVE)

components/hal/test_apps/ecc/main/test_ecc.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2023-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2023-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: CC0-1.0
  */
@@ -7,6 +7,8 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include <string.h>
+#include "ccomp_timer.h"
+#include "sys/param.h"
 #include "sdkconfig.h"
 #include "esp_log.h"
 #include "test_params.h"
@@ -136,7 +138,7 @@ TEST_CASE("ECC point multiplication on SECP192R1 and SECP256R1", "[ecc][hal]")
 
 #if SOC_ECC_CONSTANT_TIME_POINT_MUL || (CONFIG_IDF_TARGET_ESP32H2 && CONFIG_ESP32H2_REV_MIN_FULL >= 102)
 
-#define CONST_TIME_DEVIATION_PERCENT 0.002
+#define CONST_TIME_DEVIATION_THRESHOLD 2 // 0.2 %
 
 static void test_ecc_point_mul_inner_constant_time(void)
 {
@@ -152,11 +154,14 @@ static void test_ecc_point_mul_inner_constant_time(void)
     uint8_t x_res_le[32];
     uint8_t y_res_le[32];
 
-    double deviation = 0;
+    uint32_t deviation = 0;
     uint32_t elapsed_time, mean_elapsed_time, total_elapsed_time = 0;
     uint32_t max_time = 0, min_time = UINT32_MAX;
     int loop_count = 10;
 
+    // performing the operation once to warm up the cache
+    ecc_point_mul(scalar_le, x_le, y_le, 32, 0, x_res_le, y_res_le);
+
     for (int i = 0; i < loop_count; i++) {
         ccomp_timer_start();
         ecc_point_mul(scalar_le, x_le, y_le, 32, 0, x_res_le, y_res_le);
@@ -167,9 +172,9 @@ static void test_ecc_point_mul_inner_constant_time(void)
         total_elapsed_time += elapsed_time;
     }
     mean_elapsed_time = total_elapsed_time / loop_count;
-    deviation = ((double)(max_time - mean_elapsed_time) / mean_elapsed_time);
+    deviation = (((max_time - mean_elapsed_time) * 1000) / mean_elapsed_time);
 
-    TEST_ASSERT_LESS_THAN_DOUBLE(CONST_TIME_DEVIATION_PERCENT, deviation);
+    TEST_ASSERT_LESS_THAN(CONST_TIME_DEVIATION_THRESHOLD, deviation);
 
     /* P192 */
     ecc_be_to_le(ecc_p192_scalar, scalar_le, 24);
@@ -190,12 +195,12 @@ static void test_ecc_point_mul_inner_constant_time(void)
         total_elapsed_time += elapsed_time;
     }
     mean_elapsed_time = total_elapsed_time / loop_count;
-    deviation = ((double)(max_time - mean_elapsed_time) / mean_elapsed_time);
+    deviation = (((max_time - mean_elapsed_time) * 1000) / mean_elapsed_time);
 
-    TEST_ASSERT_LESS_THAN_DOUBLE(CONST_TIME_DEVIATION_PERCENT, deviation);
+    TEST_ASSERT_LESS_THAN(CONST_TIME_DEVIATION_THRESHOLD, deviation);
 }
 
-TEST(ecc, ecc_point_multiplication_const_time_check_on_SECP192R1_and_SECP256R1)
+TEST_CASE("ECC point multiplication constant time check on SECP192R1 and SECP256R1", "[ecc][hal]")
 {
     test_ecc_point_mul_inner_constant_time();
 }

components/hal/test_apps/ecc/sdkconfig.defaults

@@ -1,2 +1,3 @@
 CONFIG_ESP_TASK_WDT_EN=y
 CONFIG_ESP_TASK_WDT_INIT=n
+CONFIG_ESP_CRYPTO_DPA_PROTECTION_AT_STARTUP=n

components/mbedtls/port/ecdsa/ecdsa_alt.c

@@ -23,6 +23,8 @@
 
 #if CONFIG_MBEDTLS_HARDWARE_ECDSA_SIGN_CONSTANT_TIME_CM
 #include "esp_timer.h"
+#include "soc/chip_revision.h"
+#include "hal/efuse_hal.h"
 
 #if CONFIG_ESP_CRYPTO_DPA_PROTECTION_LEVEL_HIGH
 /*
@@ -176,9 +178,11 @@ static int esp_ecdsa_sign(mbedtls_ecp_group *grp, mbedtls_mpi* r, mbedtls_mpi* s
 #endif
         ecdsa_hal_gen_signature(&conf, sha_le, r_le, s_le, len);
 #if CONFIG_MBEDTLS_HARDWARE_ECDSA_SIGN_CONSTANT_TIME_CM
-        sig_time = esp_timer_get_time() - sig_time;
-        if (sig_time < ECDSA_CM_FIXED_SIG_TIME) {
-            esp_rom_delay_us(ECDSA_CM_FIXED_SIG_TIME - sig_time);
+        if (!ESP_CHIP_REV_ABOVE(efuse_hal_chip_revision(), 102)) {
+            sig_time = esp_timer_get_time() - sig_time;
+            if (sig_time < ECDSA_CM_FIXED_SIG_TIME) {
+                esp_rom_delay_us(ECDSA_CM_FIXED_SIG_TIME - sig_time);
+            }
         }
 #endif
         process_again = !ecdsa_hal_get_operation_result()