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- > From timbl@nxoc01.cern.ch Wed Mar 11 06:03:54 1992
- > >> Peter Deutsch's message <9203051920.AA14978@expresso.cc.mcgill.ca>
- > >> Actually, Mike Schwartz has suggested using CRC checksums,
- >
- > > From: Larry Masinter <masinter@parc.xerox.com>
- > > You can do better than that by either:
- > > a) use a good digital signature (MD5 or Snefru or ...). [...]
- > > b) rely on something else that's unique, e.g., hostid + timestamp, ISO
- > > DFR's DORs, Object Identifiers, etc.
- >
- > > We've been using 256-bit UDSNs and are happy with the scheme. I'm
- > > hoping we'll have a writeup together before next week.
- >
- > Peter, USDN is your term, so you decide what is and isn't one.
-
- I want a UDSN to be something that lets me identify the
- contents of a file and compare the contents of multiple
- files to test for uniqueness. In the long run I'd also
- like them to permit me to identify contents across
- multiple encodings, but that's harder and I'm prepared to
- wait for that.
-
- I wouldn't be so bold as to try and decide what makes a
- suitable UDSN but I hope that we can discuss the issue at
- IETF next week (since we will have so many of the players
- there) and arrive at some sort of consensus.
-
- I can say what _I_ want them for, and hope that this is
- something that would be useful to enough other people that
- we can agree to deploy something soon. Certainly there are
- a number of candidates, and Larry has named some of the
- most likely. I think something that can be applied
- retroactively (MD5?) would be preferable to something like
- hostID and timestamp, which would be hard to retrofit to
- the existing archive collections.
-
- > However, a UDI I define to be something you can use to get the object. . .
- > . . . Knowing when you have a document that
- > you have the right document is a different problem, but with a
- > good name space (like x500) you can do both operations.
-
- I'm principally interested in UDSNs at this point to allow
- comparisions between multiple items (perhaps found in disparate
- environments). I don't see how the X.500 name space can
- help me here (unless I'm misunderstanding what you mean?).
- Certainly it seems that UDIs should help locate items.
- That seems to be their raison d'etre.
-
-
- - peterd
-
- --
-
-