menu "Bootloader config" orsource "../esp_bootloader_format/Kconfig.bootloader" config BOOTLOADER_OFFSET_IN_FLASH hex default 0x1000 if IDF_TARGET_ESP32 || IDF_TARGET_ESP32S2 # the first 2 sectors are reserved for the key manager with AES-XTS (flash encryption) purpose default 0x2000 if IDF_TARGET_ESP32P4 default 0x0 help Offset address that 2nd bootloader will be flashed to. The value is determined by the ROM bootloader. It's not configurable in ESP-IDF. choice BOOTLOADER_COMPILER_OPTIMIZATION prompt "Bootloader optimization Level" default BOOTLOADER_COMPILER_OPTIMIZATION_SIZE help This option sets compiler optimization level (gcc -O argument) for the bootloader. - The default "Size" setting will add the -0s flag to CFLAGS. - The "Debug" setting will add the -Og flag to CFLAGS. - The "Performance" setting will add the -O2 flag to CFLAGS. - The "None" setting will add the -O0 flag to CFLAGS. Note that custom optimization levels may be unsupported. config BOOTLOADER_COMPILER_OPTIMIZATION_SIZE bool "Size (-Os)" config BOOTLOADER_COMPILER_OPTIMIZATION_DEBUG bool "Debug (-Og)" config BOOTLOADER_COMPILER_OPTIMIZATION_PERF bool "Optimize for performance (-O2)" config BOOTLOADER_COMPILER_OPTIMIZATION_NONE bool "Debug without optimization (-O0)" endchoice choice BOOTLOADER_LOG_LEVEL bool "Bootloader log verbosity" default BOOTLOADER_LOG_LEVEL_INFO help Specify how much output to see in bootloader logs. config BOOTLOADER_LOG_LEVEL_NONE bool "No output" config BOOTLOADER_LOG_LEVEL_ERROR bool "Error" config BOOTLOADER_LOG_LEVEL_WARN bool "Warning" config BOOTLOADER_LOG_LEVEL_INFO bool "Info" config BOOTLOADER_LOG_LEVEL_DEBUG bool "Debug" config BOOTLOADER_LOG_LEVEL_VERBOSE bool "Verbose" endchoice config BOOTLOADER_LOG_LEVEL int default 0 if BOOTLOADER_LOG_LEVEL_NONE default 1 if BOOTLOADER_LOG_LEVEL_ERROR default 2 if BOOTLOADER_LOG_LEVEL_WARN default 3 if BOOTLOADER_LOG_LEVEL_INFO default 4 if BOOTLOADER_LOG_LEVEL_DEBUG default 5 if BOOTLOADER_LOG_LEVEL_VERBOSE menu "Serial Flash Configurations" config BOOTLOADER_SPI_CUSTOM_WP_PIN bool "Use custom SPI Flash WP Pin when flash pins set in eFuse (read help)" depends on IDF_TARGET_ESP32 && (ESPTOOLPY_FLASHMODE_QIO || ESPTOOLPY_FLASHMODE_QOUT) default y if BOOTLOADER_SPI_WP_PIN != 7 # backwards compatibility, can remove in IDF 5 default n help This setting is only used if the SPI flash pins have been overridden by setting the eFuses SPI_PAD_CONFIG_xxx, and the SPI flash mode is QIO or QOUT. When this is the case, the eFuse config only defines 3 of the 4 Quad I/O data pins. The WP pin (aka ESP32 pin "SD_DATA_3" or SPI flash pin "IO2") is not specified in eFuse. The same pin is also used for external SPIRAM if it is enabled. If this config item is set to N (default), the correct WP pin will be automatically used for any Espressif chip or module with integrated flash. If a custom setting is needed, set this config item to Y and specify the GPIO number connected to the WP. config BOOTLOADER_SPI_WP_PIN int "Custom SPI Flash WP Pin" range 0 33 default 7 depends on IDF_TARGET_ESP32 && (ESPTOOLPY_FLASHMODE_QIO || ESPTOOLPY_FLASHMODE_QOUT) #depends on BOOTLOADER_SPI_CUSTOM_WP_PIN # backwards compatibility, can uncomment in IDF 5 help The option "Use custom SPI Flash WP Pin" must be set or this value is ignored If burning a customized set of SPI flash pins in eFuse and using QIO or QOUT mode for flash, set this value to the GPIO number of the SPI flash WP pin. config BOOTLOADER_FLASH_DC_AWARE bool "Allow app adjust Dummy Cycle bits in SPI Flash for higher frequency (READ HELP FIRST)" help This will force 2nd bootloader to be loaded by DOUT mode, and will restore Dummy Cycle setting by resetting the Flash config BOOTLOADER_FLASH_XMC_SUPPORT bool "Enable the support for flash chips of XMC (READ DOCS FIRST)" default y depends on !IDF_ENV_BRINGUP help Perform the startup flow recommended by XMC. Please consult XMC for the details of this flow. XMC chips will be forbidden to be used, when this option is disabled. DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU ARE DOING. comment "Features below require specific hardware (READ DOCS FIRST!)" config BOOTLOADER_FLASH_32BIT_ADDR bool default y if ESPTOOLPY_FLASHSIZE_32MB || ESPTOOLPY_FLASHSIZE_64MB || ESPTOOLPY_FLASHSIZE_128MB default n help This is a helper config for 32bits address flash. Invisible for users. config BOOTLOADER_FLASH_NEEDS_32BIT_FEAT bool default y if BOOTLOADER_FLASH_32BIT_ADDR && !ESPTOOLPY_OCT_FLASH help This is a helper config for 32bits address flash. Invisible for users. config BOOTLOADER_CACHE_32BIT_ADDR_QUAD_FLASH bool "Enable cache access to 32-bit-address (over 16MB) range of SPI Flash (READ DOCS FIRST)" depends on BOOTLOADER_FLASH_NEEDS_32BIT_FEAT && IDF_TARGET_ESP32S3 && IDF_EXPERIMENTAL_FEATURES default n help Enabling this option allows the CPU to access 32-bit-address flash beyond 16M range. 1. This option only valid for 4-line flash. Octal flash doesn't need this. 2. This option is experimental, which means it can’t use on all flash chips stable, for more information, please contact Espressif Business support. config BOOTLOADER_CACHE_32BIT_ADDR_OCTAL_FLASH bool default y if ESPTOOLPY_OCT_FLASH && BOOTLOADER_FLASH_32BIT_ADDR default n endmenu choice BOOTLOADER_VDDSDIO_BOOST bool "VDDSDIO LDO voltage" default BOOTLOADER_VDDSDIO_BOOST_1_9V depends on SOC_CONFIGURABLE_VDDSDIO_SUPPORTED help If this option is enabled, and VDDSDIO LDO is set to 1.8V (using eFuse or MTDI bootstrapping pin), bootloader will change LDO settings to output 1.9V instead. This helps prevent flash chip from browning out during flash programming operations. This option has no effect if VDDSDIO is set to 3.3V, or if the internal VDDSDIO regulator is disabled via eFuse. config BOOTLOADER_VDDSDIO_BOOST_1_8V bool "1.8V" depends on !ESPTOOLPY_FLASHFREQ_80M config BOOTLOADER_VDDSDIO_BOOST_1_9V bool "1.9V" endchoice config BOOTLOADER_FACTORY_RESET bool "GPIO triggers factory reset" default N select BOOTLOADER_RESERVE_RTC_MEM if SOC_RTC_FAST_MEM_SUPPORTED help Allows to reset the device to factory settings: - clear one or more data partitions; - boot from "factory" partition. The factory reset will occur if there is a GPIO input held at the configured level while device starts up. See settings below. config BOOTLOADER_NUM_PIN_FACTORY_RESET int "Number of the GPIO input for factory reset" depends on BOOTLOADER_FACTORY_RESET range 0 39 if IDF_TARGET_ESP32 range 0 44 if IDF_TARGET_ESP32S2 default 4 help The selected GPIO will be configured as an input with internal pull-up enabled (note that on some SoCs. not all pins have an internal pull-up, consult the hardware datasheet for details.) To trigger a factory reset, this GPIO must be held high or low (as configured) on startup. choice BOOTLOADER_FACTORY_RESET_PIN_LEVEL bool "Factory reset GPIO level" depends on BOOTLOADER_FACTORY_RESET default BOOTLOADER_FACTORY_RESET_PIN_LOW help Pin level for factory reset, can be triggered on low or high. config BOOTLOADER_FACTORY_RESET_PIN_LOW bool "Reset on GPIO low" config BOOTLOADER_FACTORY_RESET_PIN_HIGH bool "Reset on GPIO high" endchoice config BOOTLOADER_OTA_DATA_ERASE bool "Clear OTA data on factory reset (select factory partition)" depends on BOOTLOADER_FACTORY_RESET help The device will boot from "factory" partition (or OTA slot 0 if no factory partition is present) after a factory reset. config BOOTLOADER_DATA_FACTORY_RESET string "Comma-separated names of partitions to clear on factory reset" depends on BOOTLOADER_FACTORY_RESET default "nvs" help Allows customers to select which data partitions will be erased while factory reset. Specify the names of partitions as a comma-delimited with optional spaces for readability. (Like this: "nvs, phy_init, ...") Make sure that the name specified in the partition table and here are the same. Partitions of type "app" cannot be specified here. config BOOTLOADER_APP_TEST bool "GPIO triggers boot from test app partition" default N depends on !BOOTLOADER_APP_ANTI_ROLLBACK help Allows to run the test app from "TEST" partition. A boot from "test" partition will occur if there is a GPIO input pulled low while device starts up. See settings below. config BOOTLOADER_NUM_PIN_APP_TEST int "Number of the GPIO input to boot TEST partition" depends on BOOTLOADER_APP_TEST range 0 39 default 18 help The selected GPIO will be configured as an input with internal pull-up enabled. To trigger a test app, this GPIO must be pulled low on reset. After the GPIO input is deactivated and the device reboots, the old application will boot. (factory or OTA[x]). Note that GPIO34-39 do not have an internal pullup and an external one must be provided. choice BOOTLOADER_APP_TEST_PIN_LEVEL bool "App test GPIO level" depends on BOOTLOADER_APP_TEST default BOOTLOADER_APP_TEST_PIN_LOW help Pin level for app test, can be triggered on low or high. config BOOTLOADER_APP_TEST_PIN_LOW bool "Enter test app on GPIO low" config BOOTLOADER_APP_TEST_PIN_HIGH bool "Enter test app on GPIO high" endchoice config BOOTLOADER_HOLD_TIME_GPIO int "Hold time of GPIO for reset/test mode (seconds)" depends on BOOTLOADER_FACTORY_RESET || BOOTLOADER_APP_TEST default 5 help The GPIO must be held low continuously for this period of time after reset before a factory reset or test partition boot (as applicable) is performed. config BOOTLOADER_REGION_PROTECTION_ENABLE bool "Enable protection for unmapped memory regions" default y help Protects the unmapped memory regions of the entire address space from unintended accesses. This will ensure that an exception will be triggered whenever the CPU performs a memory operation on unmapped regions of the address space. config BOOTLOADER_WDT_ENABLE bool "Use RTC watchdog in start code" default y help Tracks the execution time of startup code. If the execution time is exceeded, the RTC_WDT will restart system. It is also useful to prevent a lock up in start code caused by an unstable power source. NOTE: Tracks the execution time starts from the bootloader code - re-set timeout, while selecting the source for slow_clk - and ends calling app_main. Re-set timeout is needed due to WDT uses a SLOW_CLK clock source. After changing a frequency slow_clk a time of WDT needs to re-set for new frequency. slow_clk depends on RTC_CLK_SRC (INTERNAL_RC or EXTERNAL_CRYSTAL). config BOOTLOADER_WDT_DISABLE_IN_USER_CODE bool "Allows RTC watchdog disable in user code" depends on BOOTLOADER_WDT_ENABLE default n help If this option is set, the ESP-IDF app must explicitly reset, feed, or disable the rtc_wdt in the app's own code. If this option is not set (default), then rtc_wdt will be disabled by ESP-IDF before calling the app_main() function. Use function rtc_wdt_feed() for resetting counter of rtc_wdt. Use function rtc_wdt_disable() for disabling rtc_wdt. config BOOTLOADER_WDT_TIME_MS int "Timeout for RTC watchdog (ms)" depends on BOOTLOADER_WDT_ENABLE default 9000 range 0 120000 help Verify that this parameter is correct and more then the execution time. Pay attention to options such as reset to factory, trigger test partition and encryption on boot - these options can increase the execution time. Note: RTC_WDT will reset while encryption operations will be performed. config BOOTLOADER_APP_ROLLBACK_ENABLE bool "Enable app rollback support" default n help After updating the app, the bootloader runs a new app with the "ESP_OTA_IMG_PENDING_VERIFY" state set. This state prevents the re-run of this app. After the first boot of the new app in the user code, the function should be called to confirm the operability of the app or vice versa about its non-operability. If the app is working, then it is marked as valid. Otherwise, it is marked as not valid and rolls back to the previous working app. A reboot is performed, and the app is booted before the software update. Note: If during the first boot a new app the power goes out or the WDT works, then roll back will happen. Rollback is possible only between the apps with the same security versions. config BOOTLOADER_APP_ANTI_ROLLBACK bool "Enable app anti-rollback support" depends on BOOTLOADER_APP_ROLLBACK_ENABLE default n help This option prevents rollback to previous firmware/application image with lower security version. config BOOTLOADER_APP_SECURE_VERSION int "eFuse secure version of app" depends on BOOTLOADER_APP_ANTI_ROLLBACK default 0 help The secure version is the sequence number stored in the header of each firmware. The security version is set in the bootloader, version is recorded in the eFuse field as the number of set ones. The allocated number of bits in the efuse field for storing the security version is limited (see BOOTLOADER_APP_SEC_VER_SIZE_EFUSE_FIELD option). Bootloader: When bootloader selects an app to boot, an app is selected that has a security version greater or equal that recorded in eFuse field. The app is booted with a higher (or equal) secure version. The security version is worth increasing if in previous versions there is a significant vulnerability and their use is not acceptable. Your partition table should has a scheme with ota_0 + ota_1 (without factory). config BOOTLOADER_APP_SEC_VER_SIZE_EFUSE_FIELD int "Size of the efuse secure version field" depends on BOOTLOADER_APP_ANTI_ROLLBACK range 1 32 if IDF_TARGET_ESP32 default 32 if IDF_TARGET_ESP32 range 1 4 if IDF_TARGET_ESP32C2 default 4 if IDF_TARGET_ESP32C2 range 1 16 default 16 help The size of the efuse secure version field. Its length is limited to 32 bits for ESP32 and 16 bits for ESP32-S2. This determines how many times the security version can be increased. config BOOTLOADER_EFUSE_SECURE_VERSION_EMULATE bool "Emulate operations with efuse secure version(only test)" default n depends on BOOTLOADER_APP_ANTI_ROLLBACK select EFUSE_VIRTUAL select EFUSE_VIRTUAL_KEEP_IN_FLASH help This option allows to emulate read/write operations with all eFuses and efuse secure version. It allows to test anti-rollback implemention without permanent write eFuse bits. There should be an entry in partition table with following details: `emul_efuse, data, efuse, , 0x2000`. This option enables: EFUSE_VIRTUAL and EFUSE_VIRTUAL_KEEP_IN_FLASH. config BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP bool "Skip image validation when exiting deep sleep" # note: dependencies for this config item are different to other "skip image validation" # options, allowing to turn on "allow insecure options" and have secure boot with # "skip validation when existing deep sleep". Keeping this to avoid a breaking change, # but - as noted in help - it invalidates the integrity of Secure Boot checks depends on SOC_RTC_FAST_MEM_SUPPORTED && ((SECURE_BOOT && SECURE_BOOT_INSECURE) || !SECURE_BOOT) default n select BOOTLOADER_RESERVE_RTC_MEM help This option disables the normal validation of an image coming out of deep sleep (checksums, SHA256, and signature). This is a trade-off between wakeup performance from deep sleep, and image integrity checks. Only enable this if you know what you are doing. It should not be used in conjunction with using deep_sleep() entry and changing the active OTA partition as this would skip the validation upon first load of the new OTA partition. It is possible to enable this option with Secure Boot if "allow insecure options" is enabled, however it's strongly recommended to NOT enable it as it may allow a Secure Boot bypass. config BOOTLOADER_SKIP_VALIDATE_ON_POWER_ON bool "Skip image validation from power on reset (READ HELP FIRST)" # only available if both Secure Boot and Check Signature on Boot are disabled depends on !SECURE_SIGNED_ON_BOOT default n help Some applications need to boot very quickly from power on. By default, the entire app binary is read from flash and verified which takes up a significant portion of the boot time. Enabling this option will skip validation of the app when the SoC boots from power on. Note that in this case it's not possible for the bootloader to detect if an app image is corrupted in the flash, therefore it's not possible to safely fall back to a different app partition. Flash corruption of this kind is unlikely but can happen if there is a serious firmware bug or physical damage. Following other reset types, the bootloader will still validate the app image. This increases the chances that flash corruption resulting in a crash can be detected following soft reset, and the bootloader will fall back to a valid app image. To increase the chances of successfully recovering from a flash corruption event, keep the option BOOTLOADER_WDT_ENABLE enabled and consider also enabling BOOTLOADER_WDT_DISABLE_IN_USER_CODE - then manually disable the RTC Watchdog once the app is running. In addition, enable both the Task and Interrupt watchdog timers with reset options set. config BOOTLOADER_SKIP_VALIDATE_ALWAYS bool "Skip image validation always (READ HELP FIRST)" # only available if both Secure Boot and Check Signature on Boot are disabled depends on !SECURE_SIGNED_ON_BOOT default n select BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP if SOC_RTC_FAST_MEM_SUPPORTED select BOOTLOADER_SKIP_VALIDATE_ON_POWER_ON help Selecting this option prevents the bootloader from ever validating the app image before booting it. Any flash corruption of the selected app partition will make the entire SoC unbootable. Although flash corruption is a very rare case, it is not recommended to select this option. Consider selecting "Skip image validation from power on reset" instead. However, if boot time is the only important factor then it can be enabled. config BOOTLOADER_RESERVE_RTC_SIZE hex depends on SOC_RTC_FAST_MEM_SUPPORTED default 0x10 if BOOTLOADER_RESERVE_RTC_MEM default 0 help Reserve RTC FAST memory for Skip image validation. This option in bytes. This option reserves an area in the RTC FAST memory (access only PRO_CPU). Used to save the addresses of the selected application. When a wakeup occurs (from Deep sleep), the bootloader retrieves it and loads the application without validation. config BOOTLOADER_CUSTOM_RESERVE_RTC bool "Reserve RTC FAST memory for custom purposes" depends on SOC_RTC_FAST_MEM_SUPPORTED select BOOTLOADER_RESERVE_RTC_MEM default n help This option allows the customer to place data in the RTC FAST memory, this area remains valid when rebooted, except for power loss. This memory is located at a fixed address and is available for both the bootloader and the application. (The application and bootoloader must be compiled with the same option). The RTC FAST memory has access only through PRO_CPU. config BOOTLOADER_CUSTOM_RESERVE_RTC_IN_CRC bool "Include custom memory in the CRC calculation" depends on BOOTLOADER_CUSTOM_RESERVE_RTC default n help This option allows the customer to use the legacy bootloader behavior when the RTC FAST memory CRC calculation takes place. When this option is enabled, the allocated user custom data will be taken into account in the CRC calculcation. This means that any change to the custom data would need a CRC update to prevent the bootloader from marking this data as corrupted. If this option is disabled, the custom data will not be taken into account when calculating the RTC FAST memory CRC. The user custom data can be changed freely, without the need to update the CRC. THIS OPTION MUST BE THE SAME FOR BOTH THE BOOTLOADER AND THE APPLICATION BUILDS. config BOOTLOADER_CUSTOM_RESERVE_RTC_SIZE hex "Size in bytes for custom purposes" default 0 depends on BOOTLOADER_CUSTOM_RESERVE_RTC help This option reserves in RTC FAST memory the area for custom purposes. If you want to create your own bootloader and save more information in this area of memory, you can increase it. It must be a multiple of 4 bytes. This area (rtc_retain_mem_t) is reserved and has access from the bootloader and an application. config BOOTLOADER_RESERVE_RTC_MEM bool depends on SOC_RTC_FAST_MEM_SUPPORTED help This option reserves an area in RTC FAST memory for the following features: - "Skip image validation when exiting deep sleep" - "Reserve RTC FAST memory for custom purposes" - "GPIO triggers factory reset" endmenu # Bootloader menu "Security features" # These three are the actual options to check in code, # selected by the displayed options config SECURE_SIGNED_ON_BOOT bool default y depends on SECURE_BOOT || SECURE_SIGNED_ON_BOOT_NO_SECURE_BOOT config SECURE_SIGNED_ON_UPDATE bool default y depends on SECURE_BOOT || SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT config SECURE_SIGNED_APPS bool default y select MBEDTLS_ECP_DP_SECP256R1_ENABLED select MBEDTLS_ECP_C select MBEDTLS_ECDH_C select MBEDTLS_ECDSA_C depends on SECURE_SIGNED_ON_BOOT || SECURE_SIGNED_ON_UPDATE config SECURE_BOOT_V2_RSA_SUPPORTED bool default y # RSA secure boot is supported in ESP32 revision >= v3.0 depends on (IDF_TARGET_ESP32 && ESP32_REV_MIN_FULL >= 300) || SOC_SECURE_BOOT_V2_RSA config SECURE_BOOT_V2_ECC_SUPPORTED bool default y depends on SOC_SECURE_BOOT_V2_ECC config SECURE_BOOT_V1_SUPPORTED bool default y depends on SOC_SECURE_BOOT_V1 config SECURE_BOOT_V2_PREFERRED bool default y depends on ESP32_REV_MIN_FULL >= 300 config SECURE_BOOT_V2_ECDSA_ENABLED bool default y if SECURE_BOOT_V2_ENABLED && SECURE_BOOT_V2_ECC_SUPPORTED config SECURE_BOOT_V2_RSA_ENABLED bool default y if SECURE_BOOT_V2_ENABLED && SECURE_BOOT_V2_RSA_SUPPORTED config SECURE_BOOT_FLASH_ENC_KEYS_BURN_TOGETHER bool default y if SOC_EFUSE_CONSISTS_OF_ONE_KEY_BLOCK && SECURE_BOOT && SECURE_FLASH_ENC_ENABLED # ESP32-C2 has one key block for SB and FE keys. These keys must be burned at the same time. config SECURE_SIGNED_APPS_NO_SECURE_BOOT bool "Require signed app images" depends on !SECURE_BOOT help Require apps to be signed to verify their integrity. This option uses the same app signature scheme as hardware secure boot, but unlike hardware secure boot it does not prevent the bootloader from being physically updated. This means that the device can be secured against remote network access, but not physical access. Compared to using hardware Secure Boot this option is much simpler to implement. choice SECURE_SIGNED_APPS_SCHEME bool "App Signing Scheme" depends on SECURE_BOOT || SECURE_SIGNED_APPS_NO_SECURE_BOOT default SECURE_SIGNED_APPS_ECDSA_SCHEME if SECURE_BOOT_V1_ENABLED default SECURE_SIGNED_APPS_RSA_SCHEME if SECURE_BOOT_V2_RSA_SUPPORTED default SECURE_SIGNED_APPS_ECDSA_V2_SCHEME if SECURE_BOOT_V2_ECC_SUPPORTED help Select the Secure App signing scheme. Depends on the Chip Revision. There are two secure boot versions: 1. Secure boot V1 - Legacy custom secure boot scheme. Supported in ESP32 SoC. 2. Secure boot V2 - RSA based secure boot scheme. Supported in ESP32-ECO3 (ESP32 Chip Revision 3 onwards), ESP32-S2, ESP32-C3, ESP32-S3 SoCs. - ECDSA based secure boot scheme. Supported in ESP32-C2 SoC. config SECURE_SIGNED_APPS_ECDSA_SCHEME bool "ECDSA" depends on SECURE_BOOT_V1_SUPPORTED && (SECURE_SIGNED_APPS_NO_SECURE_BOOT || SECURE_BOOT_V1_ENABLED) help Embeds the ECDSA public key in the bootloader and signs the application with an ECDSA key. Refer to the documentation before enabling. config SECURE_SIGNED_APPS_RSA_SCHEME bool "RSA" depends on SECURE_BOOT_V2_RSA_SUPPORTED && (SECURE_SIGNED_APPS_NO_SECURE_BOOT || SECURE_BOOT_V2_ENABLED) help Appends the RSA-3072 based Signature block to the application. Refer to before enabling. config SECURE_SIGNED_APPS_ECDSA_V2_SCHEME bool "ECDSA (V2)" depends on SECURE_BOOT_V2_ECC_SUPPORTED && (SECURE_SIGNED_APPS_NO_SECURE_BOOT || SECURE_BOOT_V2_ENABLED) help For Secure boot V2 (e.g., ESP32-C2 SoC), appends ECDSA based signature block to the application. Refer to documentation before enabling. endchoice choice SECURE_BOOT_ECDSA_KEY_LEN_SIZE bool "ECDSA key size" depends on SECURE_SIGNED_APPS_ECDSA_V2_SCHEME default SECURE_BOOT_ECDSA_KEY_LEN_256_BITS help Select the ECDSA key size. Two key sizes are supported - 192 bit key using NISTP192 curve - 256 bit key using NISTP256 curve (Recommended) The advantage of using 256 bit key is the extra randomness which makes it difficult to be bruteforced compared to 192 bit key. At present, both key sizes are practically implausible to bruteforce. config SECURE_BOOT_ECDSA_KEY_LEN_192_BITS bool "Using ECC curve NISTP192" depends on SECURE_SIGNED_APPS_ECDSA_V2_SCHEME config SECURE_BOOT_ECDSA_KEY_LEN_256_BITS bool "Using ECC curve NISTP256 (Recommended)" depends on SECURE_SIGNED_APPS_ECDSA_V2_SCHEME endchoice config SECURE_SIGNED_ON_BOOT_NO_SECURE_BOOT bool "Bootloader verifies app signatures" default n depends on SECURE_SIGNED_APPS_NO_SECURE_BOOT && SECURE_SIGNED_APPS_ECDSA_SCHEME help If this option is set, the bootloader will be compiled with code to verify that an app is signed before booting it. If hardware secure boot is enabled, this option is always enabled and cannot be disabled. If hardware secure boot is not enabled, this option doesn't add significant security by itself so most users will want to leave it disabled. config SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT bool "Verify app signature on update" default y depends on SECURE_SIGNED_APPS_NO_SECURE_BOOT help If this option is set, any OTA updated apps will have the signature verified before being considered valid. When enabled, the signature is automatically checked whenever the esp_ota_ops.h APIs are used for OTA updates, or esp_image_format.h APIs are used to verify apps. If hardware secure boot is enabled, this option is always enabled and cannot be disabled. If hardware secure boot is not enabled, this option still adds significant security against network-based attackers by preventing spoofing of OTA updates. config SECURE_BOOT bool "Enable hardware Secure Boot in bootloader (READ DOCS FIRST)" default n # Secure boot is not supported for ESP32-C3 revision < v0.3 depends on SOC_SECURE_BOOT_SUPPORTED && !(IDF_TARGET_ESP32C3 && ESP32C3_REV_MIN_FULL < 3) select ESPTOOLPY_NO_STUB if !IDF_TARGET_ESP32 && !IDF_TARGET_ESP32S2 help Build a bootloader which enables Secure Boot on first boot. Once enabled, Secure Boot will not boot a modified bootloader. The bootloader will only load a partition table or boot an app if the data has a verified digital signature. There are implications for reflashing updated apps once secure boot is enabled. When enabling secure boot, JTAG and ROM BASIC Interpreter are permanently disabled by default. choice SECURE_BOOT_VERSION bool "Select secure boot version" default SECURE_BOOT_V2_ENABLED if SECURE_BOOT_V2_PREFERRED depends on SECURE_BOOT help Select the Secure Boot Version. Depends on the Chip Revision. Secure Boot V2 is the new RSA / ECDSA based secure boot scheme. - RSA based scheme is supported in ESP32 (Revision 3 onwards), ESP32-S2, ESP32-C3 (ECO3), ESP32-S3. - ECDSA based scheme is supported in ESP32-C2 SoC. Please note that, RSA or ECDSA secure boot is property of specific SoC based on its HW design, supported crypto accelerators, die-size, cost and similar parameters. Please note that RSA scheme has requirement for bigger key sizes but at the same time it is comparatively faster than ECDSA verification. Secure Boot V1 is the AES based (custom) secure boot scheme supported in ESP32 SoC. config SECURE_BOOT_V1_ENABLED bool "Enable Secure Boot version 1" depends on SECURE_BOOT_V1_SUPPORTED help Build a bootloader which enables secure boot version 1 on first boot. Refer to the Secure Boot section of the ESP-IDF Programmer's Guide for this version before enabling. config SECURE_BOOT_V2_ENABLED bool "Enable Secure Boot version 2" depends on SECURE_BOOT_V2_RSA_SUPPORTED || SECURE_BOOT_V2_ECC_SUPPORTED help Build a bootloader which enables Secure Boot version 2 on first boot. Refer to Secure Boot V2 section of the ESP-IDF Programmer's Guide for this version before enabling. endchoice choice SECURE_BOOTLOADER_MODE bool "Secure bootloader mode" depends on SECURE_BOOT_V1_ENABLED default SECURE_BOOTLOADER_ONE_TIME_FLASH config SECURE_BOOTLOADER_ONE_TIME_FLASH bool "One-time flash" help On first boot, the bootloader will generate a key which is not readable externally or by software. A digest is generated from the bootloader image itself. This digest will be verified on each subsequent boot. Enabling this option means that the bootloader cannot be changed after the first time it is booted. config SECURE_BOOTLOADER_REFLASHABLE bool "Reflashable" help Generate a reusable secure bootloader key, derived (via SHA-256) from the secure boot signing key. This allows the secure bootloader to be re-flashed by anyone with access to the secure boot signing key. This option is less secure than one-time flash, because a leak of the digest key from one device allows reflashing of any device that uses it. endchoice config SECURE_BOOT_BUILD_SIGNED_BINARIES bool "Sign binaries during build" depends on SECURE_SIGNED_APPS default y help Once secure boot or signed app requirement is enabled, app images are required to be signed. If enabled (default), these binary files are signed as part of the build process. The file named in "Secure boot private signing key" will be used to sign the image. If disabled, unsigned app/partition data will be built. They must be signed manually using espsecure.py. Version 1 to enable ECDSA Based Secure Boot and Version 2 to enable RSA based Secure Boot. (for example, on a remote signing server.) config SECURE_BOOT_SIGNING_KEY string "Secure boot private signing key" depends on SECURE_BOOT_BUILD_SIGNED_BINARIES default "secure_boot_signing_key.pem" help Path to the key file used to sign app images. Key file is an ECDSA private key (NIST256p curve) in PEM format for Secure Boot V1. Key file is an RSA private key in PEM format for Secure Boot V2. Path is evaluated relative to the project directory. You can generate a new signing key by running the following command: espsecure.py generate_signing_key secure_boot_signing_key.pem See the Secure Boot section of the ESP-IDF Programmer's Guide for this version for details. config SECURE_BOOT_VERIFICATION_KEY string "Secure boot public signature verification key" depends on SECURE_SIGNED_APPS && SECURE_SIGNED_APPS_ECDSA_SCHEME && !SECURE_BOOT_BUILD_SIGNED_BINARIES default "signature_verification_key.bin" help Path to a public key file used to verify signed images. Secure Boot V1: This ECDSA public key is compiled into the bootloader and/or app, to verify app images. Key file is in raw binary format, and can be extracted from a PEM formatted private key using the espsecure.py extract_public_key command. Refer to the Secure Boot section of the ESP-IDF Programmer's Guide for this version before enabling. config SECURE_BOOT_ENABLE_AGGRESSIVE_KEY_REVOKE bool "Enable Aggressive key revoke strategy" depends on SECURE_BOOT && SOC_SUPPORT_SECURE_BOOT_REVOKE_KEY default N help If this option is set, ROM bootloader will revoke the public key digest burned in efuse block if it fails to verify the signature of software bootloader with it. Revocation of keys does not happen when enabling secure boot. Once secure boot is enabled, key revocation checks will be done on subsequent boot-up, while verifying the software bootloader This feature provides a strong resistance against physical attacks on the device. NOTE: Once a digest slot is revoked, it can never be used again to verify an image This can lead to permanent bricking of the device, in case all keys are revoked because of signature verification failure. config SECURE_BOOT_FLASH_BOOTLOADER_DEFAULT bool "Flash bootloader along with other artifacts when using the default flash command" depends on SECURE_BOOT_V2_ENABLED && SECURE_BOOT_BUILD_SIGNED_BINARIES default N help When Secure Boot V2 is enabled, by default the bootloader is not flashed along with other artifacts like the application and the partition table images, i.e. bootloader has to be seperately flashed using the command `idf.py bootloader flash`, whereas, the application and partition table can be flashed using the command `idf.py flash` itself. Enabling this option allows flashing the bootloader along with the other artifacts by invocation of the command `idf.py flash`. If this option is enabled make sure that even the bootloader is signed using the correct secure boot key, otherwise the bootloader signature verification would fail, as hash of the public key which is present in the bootloader signature would not match with the digest stored into the efuses and thus the device will not be able to boot up. choice SECURE_BOOTLOADER_KEY_ENCODING bool "Hardware Key Encoding" depends on SECURE_BOOTLOADER_REFLASHABLE default SECURE_BOOTLOADER_KEY_ENCODING_256BIT help In reflashable secure bootloader mode, a hardware key is derived from the signing key (with SHA-256) and can be written to eFuse with espefuse.py. Normally this is a 256-bit key, but if 3/4 Coding Scheme is used on the device then the eFuse key is truncated to 192 bits. This configuration item doesn't change any firmware code, it only changes the size of key binary which is generated at build time. config SECURE_BOOTLOADER_KEY_ENCODING_256BIT bool "No encoding (256 bit key)" config SECURE_BOOTLOADER_KEY_ENCODING_192BIT bool "3/4 encoding (192 bit key)" endchoice config SECURE_BOOT_INSECURE bool "Allow potentially insecure options" depends on SECURE_BOOT default N help You can disable some of the default protections offered by secure boot, in order to enable testing or a custom combination of security features. Only enable these options if you are very sure. Refer to the Secure Boot section of the ESP-IDF Programmer's Guide for this version before enabling. config SECURE_FLASH_ENC_ENABLED bool "Enable flash encryption on boot (READ DOCS FIRST)" default N select SPI_FLASH_ENABLE_ENCRYPTED_READ_WRITE help If this option is set, flash contents will be encrypted by the bootloader on first boot. Note: After first boot, the system will be permanently encrypted. Re-flashing an encrypted system is complicated and not always possible. Read https://docs.espressif.com/projects/esp-idf/en/latest/security/flash-encryption.html before enabling. choice SECURE_FLASH_ENCRYPTION_KEYSIZE bool "Size of generated XTS-AES key" default SECURE_FLASH_ENCRYPTION_AES128 depends on SOC_FLASH_ENCRYPTION_XTS_AES_OPTIONS && SECURE_FLASH_ENC_ENABLED help Size of generated XTS-AES key. - AES-128 uses a 256-bit key (32 bytes) derived from 128 bits (16 bytes) burned in half Efuse key block. Internally, it calculates SHA256(128 bits) - AES-128 uses a 256-bit key (32 bytes) which occupies one Efuse key block. - AES-256 uses a 512-bit key (64 bytes) which occupies two Efuse key blocks. This setting is ignored if either type of key is already burned to Efuse before the first boot. In this case, the pre-burned key is used and no new key is generated. config SECURE_FLASH_ENCRYPTION_AES128_DERIVED bool "AES-128 key derived from 128 bits (SHA256(128 bits))" depends on SOC_FLASH_ENCRYPTION_XTS_AES_128_DERIVED config SECURE_FLASH_ENCRYPTION_AES128 bool "AES-128 (256-bit key)" depends on SOC_FLASH_ENCRYPTION_XTS_AES_128 && !(IDF_TARGET_ESP32C2 && SECURE_BOOT) config SECURE_FLASH_ENCRYPTION_AES256 bool "AES-256 (512-bit key)" depends on SOC_FLASH_ENCRYPTION_XTS_AES_256 endchoice choice SECURE_FLASH_ENCRYPTION_MODE bool "Enable usage mode" depends on SECURE_FLASH_ENC_ENABLED default SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT help By default Development mode is enabled which allows ROM download mode to perform flash encryption operations (plaintext is sent to the device, and it encrypts it internally and writes ciphertext to flash.) This mode is not secure, it's possible for an attacker to write their own chosen plaintext to flash. Release mode should always be selected for production or manufacturing. Once enabled it's no longer possible for the device in ROM Download Mode to use the flash encryption hardware. When EFUSE_VIRTUAL is enabled, SECURE_FLASH_ENCRYPTION_MODE_RELEASE is not available. For CI tests we use IDF_CI_BUILD to bypass it ("export IDF_CI_BUILD=1"). We do not recommend bypassing it for other purposes. Refer to the Flash Encryption section of the ESP-IDF Programmer's Guide for details. config SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT bool "Development (NOT SECURE)" select SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC config SECURE_FLASH_ENCRYPTION_MODE_RELEASE bool "Release" select PARTITION_TABLE_MD5 if !APP_COMPATIBLE_PRE_V3_1_BOOTLOADERS depends on !EFUSE_VIRTUAL || IDF_CI_BUILD endchoice config SECURE_FLASH_HAS_WRITE_PROTECTION_CACHE bool default y if (SOC_EFUSE_DIS_ICACHE || IDF_TARGET_ESP32) && SECURE_FLASH_ENC_ENABLED menu "Potentially insecure options" visible if (SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT || \ SECURE_BOOT_INSECURE || \ SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT) # NOERROR # NOTE: Options in this menu NEED to have SECURE_BOOT_INSECURE # and/or SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT in "depends on", as the menu # itself doesn't enable/disable its children (if it's not set, # it's possible for the insecure menu to be disabled but the insecure option # to remain on which is very bad.) config SECURE_BOOT_ALLOW_ROM_BASIC bool "Leave ROM BASIC Interpreter available on reset" depends on (SECURE_BOOT_INSECURE || SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT) && IDF_TARGET_ESP32 default N help By default, the BASIC ROM Console starts on reset if no valid bootloader is read from the flash. When either flash encryption or secure boot are enabled, the default is to disable this BASIC fallback mode permanently via eFuse. If this option is set, this eFuse is not burned and the BASIC ROM Console may remain accessible. Only set this option in testing environments. config SECURE_BOOT_ALLOW_JTAG bool "Allow JTAG Debugging" depends on SECURE_BOOT_INSECURE || SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT select SECURE_FLASH_SKIP_WRITE_PROTECTION_CACHE if SECURE_FLASH_HAS_WRITE_PROTECTION_CACHE default N help If not set (default), the bootloader will permanently disable JTAG (across entire chip) on first boot when either secure boot or flash encryption is enabled. Setting this option leaves JTAG on for debugging, which negates all protections of flash encryption and some of the protections of secure boot. Only set this option in testing environments. config SECURE_BOOT_ALLOW_SHORT_APP_PARTITION bool "Allow app partition length not 64KB aligned" depends on SECURE_BOOT_INSECURE || SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT help If not set (default), app partition size must be a multiple of 64KB. App images are padded to 64KB length, and the bootloader checks any trailing bytes after the signature (before the next 64KB boundary) have not been written. This is because flash cache maps entire 64KB pages into the address space. This prevents an attacker from appending unverified data after the app image in the flash, causing it to be mapped into the address space. Setting this option allows the app partition length to be unaligned, and disables padding of the app image to this length. It is generally not recommended to set this option, unless you have a legacy partitioning scheme which doesn't support 64KB aligned partition lengths. config SECURE_BOOT_V2_ALLOW_EFUSE_RD_DIS bool "Allow additional read protecting of efuses" depends on SECURE_BOOT_INSECURE && SECURE_BOOT_V2_ENABLED help If not set (default, recommended), on first boot the bootloader will burn the WR_DIS_RD_DIS efuse when Secure Boot is enabled. This prevents any more efuses from being read protected. If this option is set, it will remain possible to write the EFUSE_RD_DIS efuse field after Secure Boot is enabled. This may allow an attacker to read-protect the BLK2 efuse (for ESP32) and BLOCK4-BLOCK10 (i.e. BLOCK_KEY0-BLOCK_KEY5)(for other chips) holding the public key digest, causing an immediate denial of service and possibly allowing an additional fault injection attack to bypass the signature protection. NOTE: Once a BLOCK is read-protected, the application will read all zeros from that block NOTE: If "UART ROM download mode (Permanently disabled (recommended))" or "UART ROM download mode (Permanently switch to Secure mode (recommended))" is set, then it is __NOT__ possible to read/write efuses using espefuse.py utility. However, efuse can be read/written from the application config SECURE_BOOT_ALLOW_UNUSED_DIGEST_SLOTS bool "Leave unused digest slots available (not revoke)" depends on SECURE_BOOT_INSECURE && SOC_EFUSE_REVOKE_BOOT_KEY_DIGESTS default N help If not set (default), during startup in the app all unused digest slots will be revoked. To revoke unused slot will be called esp_efuse_set_digest_revoke(num_digest) for each digest. Revoking unused digest slots makes ensures that no trusted keys can be added later by an attacker. If set, it means that you have a plan to use unused digests slots later. config SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC bool "Leave UART bootloader encryption enabled" depends on SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT select SECURE_FLASH_SKIP_WRITE_PROTECTION_CACHE if SECURE_FLASH_HAS_WRITE_PROTECTION_CACHE default N help If not set (default), the bootloader will permanently disable UART bootloader encryption access on first boot. If set, the UART bootloader will still be able to access hardware encryption. It is recommended to only set this option in testing environments. config SECURE_FLASH_UART_BOOTLOADER_ALLOW_DEC bool "Leave UART bootloader decryption enabled" depends on SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT && IDF_TARGET_ESP32 default N help If not set (default), the bootloader will permanently disable UART bootloader decryption access on first boot. If set, the UART bootloader will still be able to access hardware decryption. Only set this option in testing environments. Setting this option allows complete bypass of flash encryption. config SECURE_FLASH_UART_BOOTLOADER_ALLOW_CACHE bool "Leave UART bootloader flash cache enabled" depends on SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT && \ (IDF_TARGET_ESP32 || SOC_EFUSE_DIS_DOWNLOAD_ICACHE || SOC_EFUSE_DIS_DOWNLOAD_DCACHE) # NOERROR default N select SECURE_FLASH_SKIP_WRITE_PROTECTION_CACHE if SECURE_FLASH_HAS_WRITE_PROTECTION_CACHE help If not set (default), the bootloader will permanently disable UART bootloader flash cache access on first boot. If set, the UART bootloader will still be able to access the flash cache. Only set this option in testing environments. config SECURE_FLASH_REQUIRE_ALREADY_ENABLED bool "Require flash encryption to be already enabled" depends on SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT default N help If not set (default), and flash encryption is not yet enabled in eFuses, the 2nd stage bootloader will enable flash encryption: generate the flash encryption key and program eFuses. If this option is set, and flash encryption is not yet enabled, the bootloader will error out and reboot. If flash encryption is enabled in eFuses, this option does not change the bootloader behavior. Only use this option in testing environments, to avoid accidentally enabling flash encryption on the wrong device. The device needs to have flash encryption already enabled using espefuse.py. config SECURE_FLASH_SKIP_WRITE_PROTECTION_CACHE bool "Skip write-protection of DIS_CACHE (DIS_ICACHE, DIS_DCACHE)" default n depends on SECURE_FLASH_HAS_WRITE_PROTECTION_CACHE help If not set (default, recommended), on the first boot the bootloader will burn the write-protection of DIS_CACHE(for ESP32) or DIS_ICACHE/DIS_DCACHE(for other chips) eFuse when Flash Encryption is enabled. Write protection for cache disable efuse prevents the chip from being blocked if it is set by accident. App and bootloader use cache so disabling it makes the chip useless for IDF. Due to other eFuses are linked with the same write protection bit (see the list below) then write-protection will not be done if these SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC, SECURE_BOOT_ALLOW_JTAG or SECURE_FLASH_UART_BOOTLOADER_ALLOW_CACHE options are selected to give a chance to turn on the chip into the release mode later. List of eFuses with the same write protection bit: ESP32: MAC, MAC_CRC, DISABLE_APP_CPU, DISABLE_BT, DIS_CACHE, VOL_LEVEL_HP_INV. ESP32-C3: DIS_ICACHE, DIS_USB_JTAG, DIS_DOWNLOAD_ICACHE, DIS_USB_SERIAL_JTAG, DIS_FORCE_DOWNLOAD, DIS_TWAI, JTAG_SEL_ENABLE, DIS_PAD_JTAG, DIS_DOWNLOAD_MANUAL_ENCRYPT. ESP32-C6: SWAP_UART_SDIO_EN, DIS_ICACHE, DIS_USB_JTAG, DIS_DOWNLOAD_ICACHE, DIS_USB_SERIAL_JTAG, DIS_FORCE_DOWNLOAD, DIS_TWAI, JTAG_SEL_ENABLE, DIS_PAD_JTAG, DIS_DOWNLOAD_MANUAL_ENCRYPT. ESP32-H2: DIS_ICACHE, DIS_USB_JTAG, POWERGLITCH_EN, DIS_FORCE_DOWNLOAD, SPI_DOWNLOAD_MSPI_DIS, DIS_TWAI, JTAG_SEL_ENABLE, DIS_PAD_JTAG, DIS_DOWNLOAD_MANUAL_ENCRYPT. ESP32-S2: DIS_ICACHE, DIS_DCACHE, DIS_DOWNLOAD_ICACHE, DIS_DOWNLOAD_DCACHE, DIS_FORCE_DOWNLOAD, DIS_USB, DIS_TWAI, DIS_BOOT_REMAP, SOFT_DIS_JTAG, HARD_DIS_JTAG, DIS_DOWNLOAD_MANUAL_ENCRYPT. ESP32-S3: DIS_ICACHE, DIS_DCACHE, DIS_DOWNLOAD_ICACHE, DIS_DOWNLOAD_DCACHE, DIS_FORCE_DOWNLOAD, DIS_USB_OTG, DIS_TWAI, DIS_APP_CPU, DIS_PAD_JTAG, DIS_DOWNLOAD_MANUAL_ENCRYPT, DIS_USB_JTAG, DIS_USB_SERIAL_JTAG, STRAP_JTAG_SEL, USB_PHY_SEL. endmenu # Potentially Insecure config SECURE_FLASH_CHECK_ENC_EN_IN_APP bool "Check Flash Encryption enabled on app startup" depends on SECURE_FLASH_ENC_ENABLED default y help If set (default), in an app during startup code, there is a check of the flash encryption eFuse bit is on (as the bootloader should already have set it). The app requires this bit is on to continue work otherwise abort. If not set, the app does not care if the flash encryption eFuse bit is set or not. config SECURE_ROM_DL_MODE_ENABLED bool default y if SOC_SUPPORTS_SECURE_DL_MODE && !SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT choice SECURE_UART_ROM_DL_MODE bool "UART ROM download mode" default SECURE_ENABLE_SECURE_ROM_DL_MODE if SECURE_ROM_DL_MODE_ENABLED # NOERROR default SECURE_INSECURE_ALLOW_DL_MODE depends on SECURE_BOOT_V2_ENABLED || SECURE_FLASH_ENC_ENABLED depends on !(IDF_TARGET_ESP32 && ESP32_REV_MIN_FULL < 300) config SECURE_DISABLE_ROM_DL_MODE bool "UART ROM download mode (Permanently disabled (recommended))" help If set, during startup the app will burn an eFuse bit to permanently disable the UART ROM Download Mode. This prevents any future use of esptool.py, espefuse.py and similar tools. Once disabled, if the SoC is booted with strapping pins set for ROM Download Mode then an error is printed instead. It is recommended to enable this option in any production application where Flash Encryption and/or Secure Boot is enabled and access to Download Mode is not required. It is also possible to permanently disable Download Mode by calling esp_efuse_disable_rom_download_mode() at runtime. config SECURE_ENABLE_SECURE_ROM_DL_MODE bool "UART ROM download mode (Permanently switch to Secure mode (recommended))" depends on SOC_SUPPORTS_SECURE_DL_MODE select ESPTOOLPY_NO_STUB help If set, during startup the app will burn an eFuse bit to permanently switch the UART ROM Download Mode into a separate Secure Download mode. This option can only work if Download Mode is not already disabled by eFuse. Secure Download mode limits the use of Download Mode functions to update SPI config, changing baud rate, basic flash write and a command to return a summary of currently enabled security features (`get_security_info`). Secure Download mode is not compatible with the esptool.py flasher stub feature, espefuse.py, read/writing memory or registers, encrypted download, or any other features that interact with unsupported Download Mode commands. Secure Download mode should be enabled in any application where Flash Encryption and/or Secure Boot is enabled. Disabling this option does not immediately cancel the benefits of the security features, but it increases the potential "attack surface" for an attacker to try and bypass them with a successful physical attack. It is also possible to enable secure download mode at runtime by calling esp_efuse_enable_rom_secure_download_mode() Note: Secure Download mode is not available for ESP32 (includes revisions till ECO3). config SECURE_INSECURE_ALLOW_DL_MODE bool "UART ROM download mode (Enabled (not recommended))" help This is a potentially insecure option. Enabling this option will allow the full UART download mode to stay enabled. This option SHOULD NOT BE ENABLED for production use cases. endchoice endmenu # Security features