stealing codes - protecting my hc11(eeprom)

[ZeleC]

stealing codes

is there a way to protect my hc11(eeprom) or eprom(27c512) from being code stolen
thx

 

[M!k]

Please read this since there's almost no difference between external parallel to external serial eeprom; both can at least be copied.
**broken link removed**


Mik

 

[Jørd]

If your HC11 has built-in ROM (be it EPROM, EEPROM or similar), there ought to be a thing named "security fuse". Once set, it won't be possible to read the built-in ROM even with a designated HC11 programmer.
Whether your HC11 is equipped with EPROM/EEPROM or whatever depends on the specific version of HC11 you're using; I recommend a peek in the respective datasheet.

There is no way to read-protect an external EPROM, since the very process of reading it is needed to use it ...

Well, if you were using a smart card instead of an external EPROM, it might be possible to read-protect the smart card's memory, but then the code to implement the necessary challenge-response algorithm has to reside someplace else; it won't be a good idea to have this code sitting in a non-read-protected memory area.

 

[mk3]

If your HC11 has built-in ROM (be it EPROM, EEPROM or similar), there ought to be a thing named "security fuse".

HC11 does not have any "security fuse" to protect internal memory. Only exist one secure version ov it, labeled 68S... for some of the family members, that isn't widely available, and that has a security only for internal EEPROM.

regards

 

[BENOIT]

I sujjest you to use a PDS311 chip (WaferScale WSI)for example : this chip will be programmed with your firmware, your address decode and has SRAM
as well and can be secured.
regards,
MB.

 

[ash]

I think you should use a pic as encoder/decoder interface between hc11 and 27c512. Use simple cryption algorithm to encode send codes to eeprom! Like "Xor h50"

 

[BENOIT]

Yes But If you have the PIC that encode decode you can decode
the orginal firmware by using the PIC on an adapter built with
your EPROM programmer.
this is currently done by such manufactuers to encrypt their firmware
but seems to be weak because you can uncrypt the code they
disassembling it. usually manufacturer use PAL logic,
but also secured PAL logic can be read with 99% success.
in the WSI all PAL, memory are in the same die. it is harder to
erase the secure-bit in it.
A+
Regards,
MB.

 

[Fragrance]

PROTECTION IS A PROBLEM

Yes i agree with benoit, wafferscale can provide a better sulotion for these kind of problems another good idea is that ATMEL
www.atmel.com can provide a kind of eeprom 28c512 which also have securety bit to protect the design. see there web site get a sample and try it


regards
khalid

 

[ntxp]

It is always meaningless to protect the code from external bus, no matter what encryption you made between the mcu and external rom, the data could always read using a logic analyzer probing the bus.

So, if you want security, go to use one with internal rom, or make your own asic.

ntxp