Thursday, 8 October 2009

Wanted: Library Hardware Hacker for Desktop Tattle Tape Detector

On a quick visit to the Lee Library in Wolfson College, my all too brief conversation with librarian Anna Jones turned up a niggle with the discharge of books from the library.

As a self-service library, users must:
- scan the barcode in each book they want to borrow;
- wipe the book to demagnetise the magnetic strip inside it; (I think there was a period of charging the desensitiser too?)

On leaving the library (which also requires a swipe of the user's College Card) the book passes through a detector. If a book has not been desenstised, an alarm rings and a video recording made of the miscreant.

One of the problems with the system seems to be that having apparently checked out a book as far as the catalogue system is concerned, the user may not necessarily properly demagnetise the strip inside the book, which means that a user may inadvertently set off an alarm.

So here's where I call on the assistance of any Arduino touting hardware hackers out there. What I want is simple sensor based app that I can wave a book over and it will give me a green light for desensitised, and a red light for still sensitive. Having physically wiped a book, a user should be able to just wave it over the sensor and check they've got a green light, rather than going to the exit barrier and checking by way of seeing whether the alarm is set off or not.

I don't really know how the magnetic stripes work (nor whether they are 3M Tattle Tapes* or an alternative system), though it is a magnetism based system. But surely a simple short range detector can't be that hard to hack together? (I couldn't find anything on Make:-( Hmmm, I wonder, do the vendors sell hand held detectors anyway, that a user could use just to check they've wiped a book properly?

* I'd often wondered who sold the physical detectors that are on the entrances of pretty much every library and major chain High Street retailer, or the range of systems available, so this provided another piece of the 'how the world works' jigsaw puzzle for me:-)

PS There is another issue with the false negative detection of un-desensitised books leaving the library - apparently the detection bars are too far apart and books can slip through the middle... Which means if they are brought back to the library they may set of the alarm because they were falsely allowed out...

With an RFID system, each book has a unique RFID identifier which can be used to check the integrity of the state of the catalogue with the physical state of the library - which is not something that the current security system respects. (That is, books that enter/leave the library do so anonymously.) RFID tagged books also make intelligent/smart sleves a possibility (e.g. smartBlade. I wonder if they do tabletop RFID readers too, so you can locate books that have been left on tables? Or maybe smart miscellaneous returns shelves would be an effective halfway house?).

This reconciliation of the physical state of the library and the catalogue state isn't something that's really occurred to me before, although it does make me think of Pachube for some reason...


PPS comments still appear not to be working on this site, but they are appearing on Google SideWiki... e.g. this comment from Owen Stephens makes a couple of valid points about the potential for illegitmate user access to a security detector:
Some (not all) library staff versions of the demagnetisers do have a light to show the status of the strip.

However, I can see a problem with giving this functionality to the users - which is that it would be possible to try books that you hadn't issued to yourself on the off chance they hadn't been re-sensitised properly, and therefore identify 'stealable' books. Also libraries have cases of people defacing books to try to get rid of the security mechanisms - but they aren't always successful. Such a system would give the chance to check this.

... so before I'd be happy to look at a user facing 'check security status' option, I'd want an assessment of how this might affect security.

I suspect if you want to steal a book from any library, it's not that hard. The Library in question is open 24 hours a day, accwess controlled on entry and exit using a personal ID card, and is completely self-service. The thought above was based purely on trying to minimise embarrassment and finding ways of not putting users off borrowing books.

TEST: Sidewiki comments

[UPDATE: not working 1/11/09 - "We are currently adding documentation and robust support for retrieving all entries for a given page through the API (currently, it only returns entries above a certain quality threshold,so that set of entries may change over time)."
[ via @fawcettbj ]]


Unknown said...

Re: @ostephens comment... How about if the user-facing detector was activated for e.g. a 30s period following a valid scan of a library card, and a log kept of the uses?

That would introduce further friction into the system, and a level of accountability relating to its use?

Keren Mills said...

That sounds like a reasonable way around the problem. In fact, if the de-sensitiser is built into the surface of the self-issue machine, 3M should build in card-activation of the de-sensitiser to remove a step from the self-issue process.