Allows OTA updates to be secured via signature checks, without requiring the overhead or complexity
of a full secure boot implementation.
Uses same signing mechanisms (build system and/or espsecure.py as Secure Boot).
Requires:
* [ ] More testing
* [ ] Documentation
Added bootloader_common_get_sha256_of_partition() and esp_partition_get_sha256() - get or calculate SHA-256
digest for app and data partitions.
Added bootloader_sha256_hex_to_str() - helps to print SHA-256 digest
Added esp_partition_check_identity() - compares two partitions by SHA-256 digest
Refactoring a function esp_image_load() in bootloader space to esp_image_verify() and
bootloader_load_image(). Old name function esp_image_load is deprecated
and will remove in V4.0 version.
spi_flash/sim: Fix error test_host. Add stub for bootloader_common_get_sha256_of_partition in sim/stubs
Makes app image booting more reliable (256-bit rather than 8-bit verification.)
Some measurements, time to boot a 655KB app.bin file and run to app_main() execution.
(All for rev 1 silicon, ie no 340ms spurious WDT delay.)
80MHz QIO mode:
before = 300ms
after = 140ms
40MHz DIO mode:
before = 712ms
after = 577ms
40MHz DIO mode, secure boot enabled
before = 1380ms
after = 934ms
(Secure boot involves two ECC signature verifications (partition table, app) that take approx 300ms each with 80MHz CPU.)
Even if firmware is compiled without CONFIG_FLASH_ENCRYPTION_ENABLED
Rayionale: CONFIG_FLASH_ENCRYPTION_ENABLED controls whether boot loader
generates keys for encryption or not, but flash encryption can be
configured externally. With this change, it's possible to have boot
loader not generate keys but still have encryption working.
Also fix use of it->part
Verify 0xE9 magic byte on first write, verify entire image before
switching.
Enable verification for secure boot signature (was using invalid ifdef
guard)
