Antti Lukats wrote: > >Does anybody know how the data is scrambled on output when CP is > >enabled? Does the data get scrambled the same every time - and if so is > >it not possible to decode the scrambled data? > > it is statice XOR function (all devices except F84). No direct translation > back to PIC source (partial dissassembly of 16CXX readback possible) > NOTICE: Any key info placed into any device that has 'scrambled readback' > ie all devices except 'F' is not secure! > The scrambled readout recuces the lenght of the key in such manner that > encryption keys/algorithms that would have been secure will be cracked > by brute force attack. At new PIC16LC62A chips after all CP enabled I can read only pure "0" from any program location . So in this case XOR readback idea failed . ;) WBR Dmitry .