Code protection mechanisms for Microcontroller

Well, there is a copy bit that disables copying the content. Sure with sufficient effort that bit can be removed. This would involve opening the part and physically removing this bit. From the required gear, I doubt many are able to do it.

Rene

I've never seen PIC code that was worth protecting.

LOL!

Rufus

Well there is a logical reason for that, see if you can work it out by yourself.

That's exactly what my PhD thesis is about. There is nothing specifically on PIC18F series but Microchip hasn't done much progress in that area since their last 0.5-micron approach in PIC16F877A. Thesis covers security and code protections in wide range of microcontrollers (PIC, SX, 68HC05, H8, ST62, Z86 etc.) and some smartcards. dsPIC series though is slightly better as it employs 3M 0.35-micron process. As soon as I pass my exam and convert thesis into University Technical Report it'll be available on-line for everyone.

Here are some links:

Sergei

who uses 68HC05 (instead of 68HC08) these days?

Was this a typo or did you really test the '05?

Oliver

I tested 68HC05, 68HC11 and 68HC08 as well, but the highest security protection I've ever seen in Motorola microcontrollers was in MC68HC705C9A (I'm not talking about MC68HC05SC27 which is certainly better secured than any of MC68HCxx).

In general, MaskROM devices has higher protection than EPROM/OTP versions. And EPROM/OTP is better secured than their EEPROM/Flash successors. Of course that comparison is valid withing the same family of microcontrollers, e.g. PIC16CR57 is better than PIC16C57 and PIC16C622 is better than PIC16F628.

Sergei