[p2p-hackers] Re: Altnet goes after p2p networks with obvious patent

Ronald Wertlen rrrw at neofonie.de
Fri Jun 2 15:14:20 UTC 2006


Altnet Patents...

I took the time to read one, 5,978,791 Filed October 
24, 1997.  " Data processing system using substantially 
unique identifiers to identify data items, whereby 
identical data items have the same identifiers "
see also
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5,978,791.PN.&OS=PN/5,978,791&RS=PN/5,978,791

The patent shows some internal inconsistencies. It 
argues from a very restricted filesystem based case and 
extends without justification to other scenarios like 
databases.

"Substantially Unique Identifier"
The argument in the patent is that it is possible to 
provide access to data in a "context free" fashion by 
using the data itself, in fact ALL the data of a data 
item. Hash/Digest algorithms are specifically named 
(MD5, SHA1, etc.). We can use a three step argument to 
highlight the internal inconsistency of the patent:

i. real time constraints prevent one from simply 
increasing address space indefinitely to prevent 
collisions.

ii. the data itself is reduced to bits in a filesystem. 
In this scenario the patent works fairly well. However, 
the patent says that the scheme can be extended to 
other schemes such as databases, etc. As soon as one 
moves away from the simple filesystem case, however, 
one introduces context, as different DBs store their 
data differently to produce different hashes for the 
same data (in a context free sense).

iii. Thus it is NOT the case that the patent provides 
an apparatus which automatically ensures that the same 
data items in two different contexts have the same 
name. The TrueName method is very much context-bound!

Quote from the patent:
"In prior art systems for identifying data items there 
is no direct relationship between the data names and 
the data item. The same data name in two different 
contexts may refer to different data items, and two 
different data names in the same context may refer to 
the same data item. "



Other Loopholes:

1. P2P Systems not using DHTs are exempt.

2. Hybrid systems, like JXTA also seem to be exempt. 
[Anyone know if Altnet have been going after JXTA?]
JXTA uses its SRDI (shared resource distributed index) 
to track common resources like advertisements in the 
network - which clearly is a kind of content based 
addressing. However it's easy too see that there are 
differences.  Specifically, these are in the extensible 
Walker system. Walkers are context sensitive constructs 
which are most likely not covered by the altnet patent.

3. Hash codes based on only portions of the data.
The patent is fairly repetitive on this point.

Quote: "This invention provides, in a data processing 
system, a method and apparatus for identifying a data 
item in the system, where the identity of the data item 
depends on _all of the data_ in the data item and 
_only_ on the data in the data item."  [rw: my underscore]

4. Prior Art: as Ian Clarke suggested on this list 
previously there is bound to be prior art. Mentioned 
Prior Art:
Freenet
Xanadu.com





Besides that, it is a pretty throrough description of a 
P2P filesharing system. The authors,  David A. Farber 
and Ronald D. Lachman, had a lot of time and patience. 
They should have invested it in the Wikipedia (yeah I 
know it didn't exist back then) or something useful.

cheers, Ron

--
Ronald Wertlen



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