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bluesky - Re: Freenet's hashing algorithm

bluesky AT lists.ibiblio.org

Subject: Global-Scale Distributed Storage Systems

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  • From: hal AT finney.org
  • To: bluesky AT franklin.oit.unc.edu
  • Subject: Re: Freenet's hashing algorithm
  • Date: Thu, 15 Feb 2001 22:32:11 -0800


graydon AT venge.net writes:
> this strikes me as a conflation of matters, with serious drawbacks.
>
> * lack of friendly names
> * inability to change data without renaming/moving it
> * no actual improvement in security. the fact that the data satisfies
> the hash is vaccuous; any data will satisfy a CHK pointing to it,
> regardless of who put it there or how "true" it is. what you care about
> is that the data you retrieved is the data some party intended you to
> receive, and if you read a CHK off a tee shirt there is no reason to
> believe this CHK is any more trustworthy than a press release from the
> government of EvilLand.

A content hash should be thought of as a shorthand or abbreviation for
the document it represents. It is an unforgeable short-name, and in
principle an unforgeable address. Whether via Freenet or via some more
conventional lookup system, you can have a system to go from hash to data.

There are good uses for such documents. Not all documents need to be
updated; sometimes you want documents which *can't* be updated: legal
agreements, for example. Any time you want to make sure that someone
sees a particular revisions of a document you can give them the content
hash as a pointer. Archival or historical data can be well served with
such hashes.

Even when you need updates, content hash addressing can serve as a layer
over which you can build an update/revision system, as Freenet is doing.

Hal




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