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kmp84 · Joined: 02 Feb 2010 Posts: 345

Hi all

Had someone experience with DES and 3DES Encryption Standard, example?
I want to make some USB device(PIC with USB) talking to PC application!
I have USB stack working.
Thanks,

temtronic · Posted: Mon Dec 22, 2014 7:58 am

Microchip have several application notes about it, you'd need to 'port' their C code into CCS C, not that hard really.....

might try 'Google'. there are lots of 'hit' about it....

jay

ELCouz · Joined: 18 Jul 2007 Posts: 427 Location: Montreal,Quebec

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

Now that others have said you shouldn't use DES, it is worth to point to an algorithm to use instead: AES
The bad news is that I don't think there is a ready to use library for the CCS compiler so you will have to convert from another compiler.

You didn't mention which processor (family) you are going to use. For PIC16/PIC18 it is possible but you'll need something like 3k ROM and 512 bytes RAM just for the encryption routines alone, so try to use one of the higher capacity models. PIC24 and dsPIC will be much easier as these have more resources.

Application Note AN953 describes several encryption algorithms for PIC18, including AES.
Application Note AN821 is an AES implementation in assembly for the PIC16.

Software can be found here: http://www.microchip.com/Developmenttools/ProductDetails.aspx?PartNO=SW300052

All above software will have to be adapted for use with the CCS compiler.

Another interesting forum topic discussing AES implementations on the PIC processor: http://electronics.stackexchange.com/questions/13275/smallest-aes-implementation-for-microcontrollers

kmp84 · Joined: 02 Feb 2010 Posts: 345

kmp84 · Joined: 02 Feb 2010 Posts: 345

ELCouz · Joined: 18 Jul 2007 Posts: 427 Location: Montreal,Quebec

Your application looks like a USB Dongle for software protection....
_________________
Regards,
Laurent

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Here's my first visual theme for the CCS C Compiler. Enjoy!

kmp84 · Joined: 02 Feb 2010 Posts: 345

ELCouz · Joined: 18 Jul 2007 Posts: 427 Location: Montreal,Quebec

It's better to use your dongle actively to make some calculation part of your application or store encrypted data crucial for the application to run than some AES or DES key check.

This can easily defeated (patched) by a single jump instruction in your application executable with a disassembler.
_________________
Regards,
Laurent

-----------
Here's my first visual theme for the CCS C Compiler. Enjoy!