When changing to a different FBL while Secureboot is enabled, the META Data values generated via the HMAC Key change. As the FBL is changed, the HSE needs to recalculate the META Data using the HMAC Key; however, because the HMAC Key is deleted due to the new FBL, recalculating the META Data becomes impossible. Consequently, a reset occurs due to a verification failure at the FBL, making it impossible to launch the application. Is there a way to re-authenticate the changed FBL using the HMAC Key, thereby allowing both the FBL and the application to run normally?
When running the HSE_SRV_ID_SMR_ENTRY_INSTALL service, HseResponse returns 0xA5AA5317. This corresponds to the following definition:
#define HSE_SRV_RSP_KEY_EMPTY ((hseSrvResponse_t)0xA5AA5317UL)
This indicates that the key is empty. (As I asked previously, I suspect this response appears because that region has been erased.)
I have checked the smrEntry values. When I set a breakpoint at the point where SecureBootState is 0, I confirmed that smrEntry was entirely 0. When I set a breakpoint at the return point where Fota_S32k3_SecureBootProcess ends, I confirmed that the values appeared. At the time of return, the SecureBootState value was 1.
I would greatly appreciate it if you could guide me on how to inject the key or otherwise resolve this issue.
1) When a breakpoint is set at if(SecureBootState == 0) / Result: smrEntry = 0
2) A breakpoint at return secureBootProcessResult, the last part of the Fota_S32k3_SecureBootProcess function
