I am not sure if my answer is in line with your query but anyway thought will mention these..

MCU's do not understand HEX data like 0xFF, 0xAA. They only understand BIN data like 1111 1111 , 1001 1001. So if you have to program them, then the CODE has to be in BIN when they reach the MCU.

You will have to think why you want to convert BIN back to HEX and from there back to ASM. The results are not worth the trouble.

And if code security is the thing you are looking for, then code in a MCU that has flash memory for code and finally lock the code with the lock bits. Anybody trying to read your code off the flash ( in your absence ) will see all 0xFF. And you will be happy.

Raghu