Systems of Magic, and a request

[rising_moon]

Recently I've read a few excellent fantasy novels which were written around believable, consistent, and reasonable systems of magic. Believable magic is one of the elements that will sell me on a writer. I've enjoyed The Abhorsen Trilogy, by Garth Nix, and, most recently, The Name of the Wind, by Patrick Rothfuss.

I've learned that Brandon Sanderson, who wrote this essay on systems of magic, is going to finish Robert Jordan's 12th and final novel of the Wheel of Time series. Depending on my Lady's response to his work, I might take up the first one. :)

Unrelatedly (maybe): can any of you recommend a good history (articles, blogs, anything) of technical approaches to affixing Identity? That is, assuring that individuals are who they say they are? I'm making a study of transaction psychology -- financial services inclined but not fixed -- and would love some background data on approaches to identity assurance. Thanks!

Comments

[dilletante.livejournal.com]

yeah, so a classic downside of biometrics is that they can't be revoked or changed once someone has figured out how to duplicate them-- you're stuck with the fingerprints you have, pretty much. a second classic downside is that the actual information that constitutes the credential isn't necessarily secret-- it may even be available for anyone who wants it (anybody can see you walk and observe your gait, say; or lift a fingerprint from something you've touched). it's *assumed* to be difficult to fake, but in practice ways to fake or copy high-tech biometric credentials abound (watch the movie "gattaca" for a lot of examples, some of which occur in the modern day); and actors have been copying low-tech biometric credentials (gait, facial features, voice, mannerisms) for all of human history.

i'm going to ignore "suborn the system," because that's a danger with any system, as you say.

in short, the minimum cost of faking a biometric credential is harder to bound than a capability credential, i think. (i may have to think about this more. the classic police field tests for drunkenness ought to count as capability credentials, and they are known to be fakeable with some not-well-known cost. hm. but in general i think it holds.)

cost of revocation or change is complicated. it's not like changing your fingerprints, but you probably picked the particular cabability credential you did because it met a bunch of constraints, and they might be hard to satisfy with a different credential. you might gloss it by considering it to be the same as switching to a different biometric-- like changing all your locks. very expensive. on the other hand, some might be easy to change: "shibboleth" was another classic capability credential, and if it were found to be too easy to fake, maybe it could have been replaced by some other word that was even harder. maybe.

anyway. i think capability credentials work particularly well in situations where what you care about is really just that the authenticated person has some quality that's inherently associated with the capability you're testing-- like requiring them to pay a fee in order to prove they have money. i think at some levels of analysis they can of course be considered "having a secret" (at that level of analysis, "what you are" and "what you know" are the same, also), but i think they differ from other forms of authentication at lower levels of analysis in ways that are interesting.