esp_hmac_calculate() enabled and reset the Digital Signature (DS)
peripheral, but HMAC has no dependency on DS (the dependency runs the
other way: a DS operation uses HMAC/SHA).
The DS peripheral drives the RSA (MPI) accelerator internally, so pulsing
the DS reset also resets the RSA datapath. This coupling exists on every
target that has the DS peripheral: the MPI reset routine itself clears the
DS reset "otherwise RSA is held in reset".
esp_hmac_calculate() holds only the HMAC and SHA/AES locks, not the MPI
lock, so it can corrupt a concurrent RSA/MPI operation. On multi-core
targets (e.g. ESP32-P4, ESP32-S31, ESP32-S3) an HMAC on one core resets an
RSA op running on another core; on single-core targets (e.g. ESP32-C5) the
same corruption happens when an HMAC preempts an in-flight RSA op. The
result is a wrong RSA result or a crash in the computation.
Remove the DS peripheral enable/reset from the HMAC path. SHA, which HMAC
depends on, is enabled independently, so the HMAC output is unchanged.
This also drops a few redundant register writes.
The Key Manager holds a key usage register, thus, the Key Manager peripheral
clock must be enabled even for efuses-based key operations to route the
crypto operations to correctly to the efuses (default is Key Manager)
Ashish Sharma
nilesh.kale
harshal.patil
Aditya Patwardhan
Laukik Hase
Mahavir Jain