>Which is exactly *not* what is asked for.

Well, it is really.

>Obfuscating works - if at all - only when the
>opponent does not know the algorithm.

Which is true of any secure bootloader.

Realistically all the OP is looking for is a way of distributing a software 
update without anybody between the software provider and the destination 
hardware being able to disassemble it to get at the IP. Precisely how this 
is done is up to the bootloader writer. 

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