[p2p-hackers] Re: Altnet goes after p2p networks with obvious patent
rrrw at neofonie.de
Fri Jun 2 15:14:20 UTC 2006
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 "
The patent shows some internal inconsistencies. It
argues from a very restricted filesystem based case and
extends without justification to other scenarios like
"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
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. "
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
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.
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