Arggh. Wrong link. Apologies to all and thanks to James McKinney. That's what I get for having that many tabs open.
https://sunlightfoundation.com/blog/2014/03/20/a-little-math-could-make-identifiers-a-whole-lot-better/ On Thu, Mar 20, 2014 at 5:44 PM, James McKinney <ja...@opennorth.ca> wrote: > Do you mean this post? > > > https://sunlightfoundation.com/blog/2014/03/20/a-little-math-could-make-identifiers-a-whole-lot-better/ > > > On Mar 20, 2014, at 3:44 PM, Tom Lee <t...@sunlightfoundation.com> wrote: > > Thanks again to everyone who helped me think through how government's > approach to disclosing identifiers could be improved through checksums, > tokenization and related techniques -- it was extremely helpful. The > resulting post is here: > > > https://sunlightfoundation.com/blog/2013/07/25/the-sunlight-foundations-comments-on-the-faas-proposed-open-data-policy/ > > I'd be grateful for any feedback -- or, especially, corrections -- that > might occur to you. > > > On Thu, Feb 6, 2014 at 3:49 PM, Tom Lee <t...@sunlightfoundation.com>wrote: > >> We've been kicking around an idea at Sunlight that aims to use >> cryptographic ideas to resolve some of the concerns around the publication >> of publicly identifiable information in government disclosures. I could use >> some smart people to tell me what's dumb about it. >> >> We often face challenges related to disambiguating entities: is the John >> Smith who gave political donation A the same John Smith that gave political >> donation B? One obvious solution to this problem is to push to expand the >> information that's collected and disclosed -- if we had John's driver's >> license number (DLN), for instance, it'd be easy to disambiguate these >> records. But that could introduce privacy concerns for John. One approach >> to this problem (which I don't think government has tried) is employing a >> one-way hash. >> >> Obviously the input key space for DLNs and most other personal ID numbers >> is so small that reversing this with a dictionary attack would be trivial. >> You can add a salt, but only on a per-entity basis (not a per-record basis) >> if you want to preserve the capacity to disambiguate. That in turns calls >> for a lookup table in which the input keys are stored, which kind of >> defeats the point of using a hash (you might as well just assign random >> output IDs for each input ID). I would worry about government's ability to >> keep this lookup table secure, and I worry about the brittleness of such a >> system. >> >> Alternately, you can use a single system-wide secret (or set of secrets) >> to transform inputs into reliable outputs. I think this is less brittle and >> maybe easier to preserve as a secret, but this system might be too easily >> reversible given the ability to observe its outputs and know the universe >> of possible inputs. I'm unsure of the cryptographic options that might be >> appropriate here. >> >> For all I know, the lack of implementations using this kind of one-way >> transformation isn't about government sluggishness but rather about its >> feasibility. I'd be very curious to hear folks ideas on this score, though. >> My general hunch is that something must be possible -- even a few bits' >> worth of disambiguating information would be hugely useful to us, and >> presumably you're not leaking important amounts of information by, say, >> sharing the last digit of a DLN. So there must be a spectrum of options. >> But as is probably apparent, I don't think I've got a handle on how to >> think about this problem rigorously. >> >> Tom >> > > > -- > You received this message because you are subscribed to the Google Groups > "sunlightlabs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sunlightlabs+unsubscr...@googlegroups.com. > To post to this group, send email to sunlightl...@googlegroups.com. > Visit this group at http://groups.google.com/group/sunlightlabs. > For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to the Google Groups > "sunlightlabs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sunlightlabs+unsubscr...@googlegroups.com. > To post to this group, send email to sunlightl...@googlegroups.com. > Visit this group at http://groups.google.com/group/sunlightlabs. > For more options, visit https://groups.google.com/d/optout. >
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