piclist 2001\01\02\115241a >
Thread: How difficult is it to bypass the PIC security fuse toreadback the firmware
face BY : M. Adam Davis email (remove spam text)

You can read the archives about this subject.  No one has advertised or
made mention of the ability to break the fuse on the 'f8xx series (which
doesn't mean it hasn't been done), but there are companies which will
break into earlier pics for between $500 and $5000 to retrieve the code.

Typically they need several PICs with the same code on them, so it's still
a delicate issue to deal with electrically, even for the older pics.

Essentially you need to decide what your code is worth to someone else.
If a company wants your code, then it probably will simply hire someone to
replicate the functions of the chip.  If your chip is aimed at the
consumer or hobbyist markets, then you probably don't have to worry unless
it is very popular, or it is integral to a security/access system (such as
the chips in satellite and cable receivers).

The key here being - can it be replicated without knowing the code?  Are
there keys, or some sort of encryption/encrypted information in the chip
which cannot be divined by knowing the input and output.  If this is not
the case, then you don't really need to worry about someone breaking into
it (it's cheaper to hire someone on the piclist to make a functionally
similar device ;-).  If, however, this is the case, then you need to
determine your target cracker's resources and desire for the code, and
weigh that against the R&D and lost profit you may face once broken.


Neil Gandler wrote:
> I am working with a PIC16C77 for a new design and I would like to know how difficult it is to defeat the security fuse
> that prevents readback of firmware. Now I know, one can try to reverse engineer your design by monitoring the behavior of the PIC I/O, I still would like to know how effective the security fuse is.
> --
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> TakeThisOuTpiclist-unsubscribe-requestspammitvma.mit.edu

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See also: www.piclist.com/techref/microchip/devices.htm?key=pic
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