[Noisebridge-discuss] RFID tag research (was: Problem: people seeing NB as a backup shelter)

Henner Zeller h.zeller at acm.org
Sat May 10 04:41:20 UTC 2014


Hi,
Alright, as discussed in the other thread, lets install RFID readers for
physical access control to Noisebridge to address one of the problems we
have right now: simple access for members/associate members (or whatever
these are called nowadays). Initially at the top door, later as well at the
front door (in parallel to physical key and keypad).

I have researched the space a bit. For one, we have a 950Mhz reader and a
couple of tags. The experiments with these (
https://www.noisebridge.net/wiki/RFID ) had some trouble getting the actual
device ID, only the re-writeable part (which made them hard to use a
non-forgeable entry keys). These tags might actually be really useful to
make sure that tools and stuff don't 'vanish'.

So what else is there, in particular used for entry systems:

125kHz tags exist, are very simple and allow to give out an ID. They are
pretty cheap (~30cent for a credit-card size). Their use is limited and
cannot be re-written.

Most promising I think is the NFC range of 13.57Mhz. These cards are as
well pretty cheap (~30cent each at first look on ebay; other form-factors
such as stickers exist). They come in ranges of capabilities: they all have
a unique ID and allow to write data to it (from 64 byte up to a couple of
kB). More higher end cards have encryption on-board. One of the great
advantages (IMHO) is, that most common smart-phones now come with an NFC
reader which would allow for some simple hacking. We can start with a
simple scheme by just reading the ID (which is more level security than we
need at NB), but playing with the memory for more things (changing random
number on each entry, or a section with your PGP public key..).

Anyway, unless there are good technical objections to using these kind of
NFC cards, I am doocratically ordering a bunch of these 13.57Mhz cards and
get readers and start playing; I'll donate them to NB.
(Anyone has 13.57Mhz cards lying around already?)

Henner
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