[bittorrent] New P2P protocols
arachnid at notdot.net
Sun Mar 27 21:05:42 EST 2005
On 28/03/2005, at 1:01 PM, mgp at ucla.edu wrote:
> Just a warning about Online Codes: they _are_ patented by Digital
> Fountain. In fact, the Online Codes paper cited  actually fell under
> the scope of DF's patents, unbeknownst to the authors. As a result,
> (or perhaps just before) the authors started the company Rateless ,
> they developed new "rateless codes, based on decoders that don't use
> chain-reaction, message passing or belief-propagation techniques." If
> you've read the Online Codes paper, you'll find this quite interesting,
> since this is how Online Codes and practically every other similar code
> based on sparse graphs works. Unfortunately, I haven't seen any papers
> their new technique -- perhaps they are keeping quiet until they
> patents on it.
Yup, I'm aware of that unfortunate circumstance. As I stated, though,
for myself it doesn't apply, as I live in New Zealand. I still think
it's worth implementing, even if it means that only non-us users can
use that portion of it.
> Before I found out that Online Codes were wrapped up in an IP
> quagmire, I
> implemented the encoder and decoder from the algorithm in the paper,
> including niceties such as a "pretty" interface (allowing it to be used
> as a library in any application) and a disk cache for improved
> performance. Unfortunately, only after I finished it all did I realize
> would get sued if it ever saw the light of day under the GPL.
You could publish it under a more permissive license, with the proviso
that it not be used in the US without a patent license.
> Now, I haven't read the paper on homomorphic hashing for rateless
> but I was wondering if after applying it to a "vanilla" rateless code,
> would the new code fall within the scope of Digital Fountain's patents?
> Unfortunately(or, depending on your point of view, it was simply good
> fortune), IANAL -- but if not, it might be something worth pursuing. If
> needed, you can build on what I've written. (Right now it is in Java,
> it should be easily translated into any OO-language.)
Having skimmed one of the patents, I believe it would still be covered:
The only change required to implement homomorphic hashing is to change
the xor for block combination to addition modulo a large prime, and the
patent is very wide in scope - if I remember correctly, it applies
regardless of how you amalgamate blocks.
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