Pic to Pic Firmware upgrade

[Jumper]

Write your own loader in PBP, this link will tell you how. Encrypt the hexfile on the PC-side and let the loader read the data serially or whatever way and at the same time decrypt it and writing the code to the codespace.

This way the hexfile is safe all the way ........ and I trust Microchip's ability to keep the code inside the chip after I have set it to CP. At lest for a reasonable cost and effort :-)


http://www.picbasic.co.uk/forum/showthread.php?t=4498


Maybe it is time to start a real thread with bootloaders in this forum. That link is full with errors and is quite long.... An I2C decryption loader using an external EEprom became 8 kbytes and is working great.

And no, I will not tell you my encryption

/me

[mister_e]

There's still the option to use and understand asm and some some open source ones. As far as i remind TinyBootloader is one of them.

But yeah... if you plan to change the code to add your own encryption, you will also need to change the PC software as well.

[Josuetas]

It will be... a bit complex..

First i used th microchip bootloader, it works nice and gives the Software in Visual Basic to be modified and also the ASM to be modified.

Not an easy task again.... it is always hard to understand other peoples coding, and you will have to do this twice (ASM and Software loader).

The PDF that comes with the bootloader explains as much as it can the transfer protocol.

Recommended to avoid your hex file being copied: Change the bootloader and the software.. change the C libraries included to encrypt your file. Protect the bootloader code space (only in 18F) otherwise someone could just overwrite it with original and then reading everything!!.

Its a hard but nice job to do because you can always use it for your next projects

[Jumper]

Code protect the entire PIC not just the boot block. Then no-one can do anything except from inside the loader.

And with a home-made loader, creative codeing and 3 months later I bet it is protected even from the developer. But then, just erase it and start all over again.



/me

[Josuetas]

Off Course!! Protect the whole device!!

I was thinking on protect the boot block from being writen or erased... 18F has special protection for the boot block!

[jason]

My goal here is almost exactly like your all talking about. I'm thinking of having an 8 pin dip socket on my new version of an on going production board. the goal would be to send a client a 15 cent serial eeprom that has updated encrypted firmware code in it. Once power is supplied, the bootloader would decrypt the code in the serial eeprom and program itself. Without the decrypted code from ever seeing daylight and having at least 64bit encryption method It should be next to impossible from using it to make clones. Once programed a green light would come on and the client could power down and take out the ereased serial eeprom and through it away.

Any suggestions would be greatly aprpeciated. Here in this topic you guys have givin me several helpful tips, Thank you.