Gate these notes on SOC_SECURE_BOOT_V2_ECC in addition to the ECDSA
peripheral P-384 capability, so they are not rendered for targets
without the ECDSA Secure Boot scheme.
Previously the bootloader unconditionally revoked unused secure boot key
digest slots while permanently enabling secure boot on the first boot,
ignoring CONFIG_SECURE_BOOT_ALLOW_UNUSED_DIGEST_SLOTS. Now the config is
honored on this path too: when set, the unused digest slots are left
un-revoked. This is safe as long as the debug and download interfaces are
disabled.
Update the Kconfig help and the Secure Boot v2 guide (en and zh_CN)
accordingly.
ECDSA based Secure Boot V2 is not functional for certain input vectors on
ESP32-C5/C61/H2/P4 and on the preview targets ESP32-H4/H21. RSA based Secure
Boot V2 is the recommended scheme where the SoC supports it. This issue will be
fixed in a future hardware ECO revision; more details will be shared through the
hardware errata document.
A new hidden Kconfig option SECURE_BOOT_V2_ECDSA_INSECURE marks the affected
mass-production SoCs (ESP32-C5/C61/H2/P4). On these SoCs, when hardware Secure
Boot V2 is enabled, the ECDSA (V2) signing scheme is no longer offered by
default; it must be turned on explicitly via SECURE_BOOT_V2_FORCE_ENABLE_ECDSA
under "Allow potentially insecure options" (CONFIG_SECURE_BOOT_INSECURE). App
signing without hardware Secure Boot is not affected. Note that ESP32-C61 has no
RSA based Secure Boot V2, so it has no Secure Boot scheme enabled by default.
The preview targets ESP32-H4 and ESP32-H21 mark ECDSA Secure Boot V2 as not
supported in their SoC capabilities instead of using the option above. As
ESP32-H4 has no other Secure Boot V2 scheme, Secure Boot is disabled entirely on
it; ESP32-H21 retains RSA based Secure Boot V2.
The security documentation keeps the ECDSA Secure Boot V2 content visible and
adds a warning describing the limitation (including that ECDSA Secure Boot V2 on
ESP32-C61 is not recommended for production). CI apps that exercise ECDSA Secure
Boot V2 on the affected SoCs set CONFIG_SECURE_BOOT_V2_FORCE_ENABLE_ECDSA
accordingly.
Ashish Sharma
Marius Vikhammer
Aditya Patwardhan
Mahavir Jain
renpeiying
nilesh.kale
Zhang Shuxian
Zheng Zhong
Peter Dragun
harshal.patil
shenmengjing
caixinying-git
kirill.chalov
Supreet Deshpande