There are a few locks in this space, all somewhat different.<p>I got more interested in them back when I first learned of Airbnb (2008 or 2009), and thought about how much of a pain handling keys would be; a reprogrammable lock would be ideal. Unfortunately, until BT 4.0LE on the iPhone 4S, there wasn't really a good way to do this other than conventional NFC (giving people tags in advance, and then remote-acl modifications to let them into units), which required wifi or other data on every lock.<p>So there's August (BT 4.0 LE, no local network). Probably the nicest industrial design. Fits over the inside part of a single cylinder deadbolt. Lack of network in the lock makes it harder to do a networked audit log.<p>Lockitron (a YC company) -- I kind of hated the first generation of their product, but the second generation, shipping soon, is close to the August, plus has built-in Wifi. I'm not sure if it can work in entirely-local mode, which IMO is a key feature.<p>Neither of these replaces the actual lock. This is both a plus and a minus.<p>Schlage, ilco, etc. have a combination of consumer and commercial locks with NFC, touchscreen, or bluetooth. Some have monthly service charges.<p>Sadly, no one makes a really good cryptographic lock (i.e. something which does challenge response authentication, rather than just passing a string), as far as I can tell. I haven't looked at the August or Lockitron 2.0 protocols, though, but all the big commercial lock company products are a bit mediocre for security. This doesn't matter so much for doors as it does for safes or other security containers. I had really high hopes for the smartcard/iButton based locks, but those just send a serial number, too, and are thus easily intercepted or spoofed.<p>Kaba-Mas makes probably the best electromechanical lock, the X09 (and new X10 coming); they're about $1k. Unfortunately even those only work as locks and are deficient as seals.<p>The gold standard seems to be the integrated building system where everything is networked and centrally managed (HID or whatever), but I think there's a great opportunity beyond the single-door residential that all of these seem to be going after, but below the integrated facility system. Something designed for <200 users, 2-5 doors, cloud managed for changes, and local config pushed to the locks for instant access.<p>Maybe could make it work using Lockitron or August hardware, or some commodity hardware from one of the lock companies.