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bootloader protected by password

Question asked by dumoulin.laurent on Jan 15, 2016
Latest reply on Jan 15, 2016 by Clive One

I would like to udpdate the microcontroller STM32F42xxx SW without having access to Boot pins ( hardwired to boot0 = 0 boot 1 = 0) and by using USART port.
code is stored in internal flash memory containing SW code ( code run fom flash) through the USART bus by using existing bootloader. I would like this update be protected by password.

first operation :  during 5 first seconds after start, CPU waits for password through UART. if not received it jump to operational application, otherwise it jumps to bootloader adress in System memory.
second operation : terminal sends commands to change flash content to bootloader firmware
third operation : exit with go command or HW reset.

my question's :
-Do you see any difficulties to develop this ?
- in case of wrong flash write , power off during flash donwloading,... there is a risk that SW code is corrupted and thus never be able to access flash memory without opening box . Am I right ? or Is a protection mechanism exists that detect invalid I-code ( as soon as one is met) and jump to bootloader ?

maybe other alternative to my problem ?

Thanks for the Help.