Re: Cisco Flash help needed

[Simon Lockhart <simonl () rd bbc co uk>]

> I've come across 2 CRCs so far - a 32 bit one used on the Class A cards, 
> and a 16 bit one used on the Class B cards. I've tried a standard crc32 
> routine (stolen from ssh), but it doesn't match the CRC reported by the 
> router. Is there anyone good at understanding CRC routines who can help me 
> reverse-engineer the cisco CRC, or perhaps does someone have some inside 
> information they would like to share?

After some suggestions from various people, I tried uploading a few test 
files onto a Cisco and seeing how the CRCs worked out. It turns out it's 
not a true CRC at all, but rather a variation on the TCP checksum 
algorithm.

> Please don't ask me for the code yet! I'll let the list know when it's 
> available...

v0.1 of the code is now available (read only at the moment):

        ftp://ftp.bbc.co.uk/pub/ciscoflash/

Enjoy,

Simon
-- 
Simon Lockhart                       |   Tel: +44 (0)1737 839676 
Internet Engineering Manager         |   Fax: +44 (0)1737 839516 
BBC Internet Services                | Email: Simon.Lockhart () bbc co uk 
Kingswood Warren,Tadworth,Surrey,UK  |   URL: http://support.bbc.co.uk/