[p2p-hackers] Online Codes

[Paul Campbell]

On Tue, Feb 15, 2005 at 01:52:41AM -0800, Michael Parker wrote:
> Does anyone know what happened to the "Online Codes" Sourceforge 
> project, listed at http://sourceforge.net/projects/onlinecodes? I'm 
> asking here for two reasons: First, because Online Codes [1, 2] would be 
> a great tool in peer-to-peer applications, so I thought someone here 
> might have followed the project while it was still active. Second, I've 
> written a solid library implementation of the Online Codes 
> encoding/decoding algorithm described in the aforementioned papers. 
> Alas, only after I implemented it did I find out that the authors' 
> company, Rateless, had patented it (or, so they allude to on their web 
> site www.rateless.com, Digital Fountain owned the IP). I was thinking of 
> releasing it under the GPL, but now that I've discovered patents are 
> involved that seems like a very bad idea.

There are additional papers out there. There are essentially two
implementations of the idea. First, there's the "LT Codes" and "Raptor
Codes". Second, there's the "Online Codes". Both are very similar in a lot
of ways.

There are also some fundamental problems. See this one:
http://citeseer.ist.psu.edu/695965.html

I didn't know that Online codes have now been patented. However, if you
consider the code, you've got essentially two pieces. First, there's the
LDPC cipher being used in erasure-handling only. Second, there's the inner
error correction cipher. The inner cipher is what makes the fundamental
difference between LT Codes and Online Codes. However, there is absolutely
nothing to say that you can't use say a punctured rate-1 outer code
(repitition-style codes) with a suitable scrambler, or vary the inner code
with something that gives equivalent performance (even a BCH code). Patents
only work as long as you implement ALL the features of the patent.