This isn't a Linux question, but I don't know where else to turn.

I need to write an encrypted bootloader for a dsPIC33, and I don't know what encryption algorithm to use, or even where to start looking. It needs to be a moderately strong symmetrical algorithm that doesn't take up a lot of code space. So I guess that provides some boundaries. The value of the program it will be protecting is not particularly high, but I have a lot of time invested in developing it. Mostly, I don't want to see a knockoff of my product appear on ebay with my code installed, and the IP thief referring questions to me - which I have run into before.

I don't need help with coding or any of that. I just need a starting point with the names of some publicly available encryption algorithms that would be appropriate for my needs.

Based on metaschima's post here, I decided to try twofish first.

http://www.linuxquestions.org/questi...0/#post5346410

Symmetric encryption algorithms would be AES (Rijndael), Twofish, Serpent, Threefish.

1 members found this post helpful.

Hi veerain,

Of those, which is the simplest to implement with the smallest code footprint? It's just going to be used to flash new firmware into either a dsPIC33FJ64MC802 or a dsPIC33FJ128MC802. I haven't gotten the twofish test to work yet. I'm going through the platform.h at the moment to try to set that up for Linux. After that, I'll do the same on the dsPIC33.

Well I don't know which is simplest and also smallest. But theefish part of skein is the newest one.

Thanks for the help, veerain. Getting the twofish code from the author's site to work was a problem, as it was written for Borland C, as well as being old. Combine that with a newbie to keys and encryption, and you see the problem. But, I've managed to get one of the public versions going, and have cut the object size down to something manageable on the PIC. More importantly, it actually worked! =) So, looks like this is a go.

Cheers!

Many have ported skein and threefish to embedded systems. See skein website.