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docs: Adds secure_boot_v2 for ESP32-C3 ECO3

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KonstantinKondrashov
2021-04-06 21:58:01 +08:00
parent 4e23f9f3b7
commit 9295e54c9d
4 changed files with 19 additions and 14 deletions
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6
docs/en/security/flash-encryption.rst
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@@ -485,8 +485,7 @@ When using Flash Encryption in production:
- Do not reuse the same flash encryption key between multiple devices. This means that an attacker who copies encrypted data from one device cannot transfer it to a second device.
:esp32: - When using ESP32 V3, if the UART ROM Download Mode is not needed for a production device then it should be disabled to provide an extra level of protection. Do this by calling :cpp:func:`esp_efuse_disable_rom_download_mode` during application startup. Alternatively, configure the project :ref:`CONFIG_ESP32_REV_MIN` level to 3 (targeting ESP32 V3 only) and select the :ref:`CONFIG_SECURE_UART_ROM_DL_MODE` to "Permanently disable ROM Download Mode (recommended)". The ability to disable ROM Download Mode is not available on earlier ESP32 versions.
:not esp32: - The UART ROM Download Mode should be disabled entirely if it is not needed, or permanently set to "Secure Download Mode" otherwise. Secure Download Mode permanently limits the available commands to basic flash read and write only. The default behaviour is to set Secure Download Mode on first boot in Release mode. To disable Download Mode entirely select select the :ref:`CONFIG_SECURE_UART_ROM_DL_MODE` to "Permanently disable ROM Download Mode (recommended)" or call :cpp:func:`esp_efuse_disable_rom_download_mode` at runtime.
:not esp32c3: - Enable :doc:`Secure Boot <secure-boot-v2>` as an extra layer of protection, and to prevent an attacker from selectively corrupting any part of the flash before boot.
:esp32c3: - Enable Secure Boot (not supported yet) as an extra layer of protection, and to prevent an attacker from selectively corrupting any part of the flash before boot.
- Enable :doc:`Secure Boot <secure-boot-v2>` as an extra layer of protection, and to prevent an attacker from selectively corrupting any part of the flash before boot.
Possible Failures
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@@ -760,8 +759,7 @@ Flash encryption protects firmware against unauthorised readout and modification
- Not all data is stored encrypted. If storing data on flash, check if the method you are using (library, API, etc.) supports flash encryption.
- Flash encryption does not prevent an attacker from understanding the high-level layout of the flash. This is because the same AES key is used for every pair of adjacent 16 byte AES blocks. When these adjacent 16 byte blocks contain identical content (such as empty or padding areas), these blocks will encrypt to produce matching pairs of encrypted blocks. This may allow an attacker to make high-level comparisons between encrypted devices (i.e. to tell if two devices are probably running the same firmware version).
:esp32: - For the same reason, an attacker can always tell when a pair of adjacent 16 byte blocks (32 byte aligned) contain two identical 16 byte sequences. Keep this in mind if storing sensitive data on the flash, design your flash storage so this doesn't happen (using a counter byte or some other non-identical value every 16 bytes is sufficient). :ref:`NVS Encryption <nvs_encryption>` deals with this and is suitable for many uses.
:not esp32c3: - Flash encryption alone may not prevent an attacker from modifying the firmware of the device. To prevent unauthorised firmware from running on the device, use flash encryption in combination with :doc:`Secure Boot <secure-boot-v2>`.
:esp32c3: - Flash encryption alone may not prevent an attacker from modifying the firmware of the device. To prevent unauthorised firmware from running on the device, use flash encryption in combination with Secure Boot (not supported yet).
- Flash encryption alone may not prevent an attacker from modifying the firmware of the device. To prevent unauthorised firmware from running on the device, use flash encryption in combination with :doc:`Secure Boot <secure-boot-v2>`.
.. _flash-encryption-and-secure-boot: