# Electromechanical Door Locks

1. Oct 30, 2008

### cepheid

Staff Emeritus
Hi,

I'm wondering what the point of electromechanical door locks is. But first, the disclaimer:

Don't get me wrong. I'm a big fan of electronics. In fact, it's one of the few areas of engineering that excites me. I'm not that crazy about mechanics or mechanical systems. That's my personal bias, because my background is in electrical engineering (and physics), and I tend to gravitate towards high tech stuff and am interested in emerging technologies and the closing gap between fundamental science and the applications that stem from it.

That having been said, really, what is the point of elaborate powered door locking mechanisms (aside from in vehicles where they're quite handy)? Some of the newer "FOB" type systems seem pretty reliable. But magnetic stripe card reader door locks? Please. Give me a break. I'm living in a building with these hotel style locks on the doors right now. They're SO flaky! It seems like unless you stick the card in the reader in exactly the right way, at exactly the right speed, you get an error. What advantage does this offer? Is it JUST better security? Because it seems to me that, by comparison, a simple mechanical locking system can't fail nearly as often.

2. Oct 30, 2008

### mgb_phys

For hotels it allows you to change the locks after each guest, so a lost or copied key has no value.
For an apartment block frontdoor it has an advantage that you can restrict access to current tenants instead of all previous tenants - their ex-boyfriends, their mothers, babysitters and every ex-cleaner or janitor.

We has a similair problem, our labs were protected by high security mechanical locks cost something like $500 each and had to be replaced every year in case an ex-student had a copy of a key. My suggestion was to just put all the old lock barrels with their known keys attached in a bucket - shake them up and reinstall them at random. Since nobody would know which new lock their old key fitted it would be secure. Last edited: Oct 30, 2008 3. Oct 30, 2008 ### Proton Soup traditional door locks are ridiculously insecure << post edited by berkeman to remove links >> Last edited by a moderator: Nov 11, 2008 4. Oct 31, 2008 ### Danger And one advantage of the touchpad system is that you can't lose your key. 5. Oct 31, 2008 ### Topher925 Everyplace I have worked had RFID integrated into our people tags. Just swipe quickly and the door unlocks. Pretty convenient if you ask me. 6. Oct 31, 2008 ### FredGarvin Honestly, I always slam the automakers for throwing idiotic ideas at vehicles just so they can market something new or different on their vehicles. A lot of times it has nothing to do with making it a better car but more of a marketing and sales gimmick. While mechanical locks are notoriously insecure, entire door mechanisms, regardless of the lock, are insecure. I can get in both of my vehicles without going anywhere near the locks. 7. Oct 31, 2008 ### stewartcs I think it is mainly for convenience. We use them at work as well to restrict access to employees only. CS 8. Oct 31, 2008 ### DaveC426913 Something I learned in security. No lock - anywhere, including Fort Knox - is designed to keep a ne'er-do-well from getting in. A lock's purpose is to discourage the attempt to enter, or, failing that, to delay the ne'er-do-well long enough to attract attention. It's a subtle distinction but an important one. 9. Oct 31, 2008 ### mgb_phys Or in the case of a car - to force them to break a side window that costs £150 to replace to discover that surprisingly, there is nothing of value in my 15year old £500 wreck! grumble...grumble..should leave the thing unlocked...grumble..grumble.... 10. Oct 31, 2008 ### mgb_phys 11. Nov 11, 2008 ### Enthalpy Anything that has electronics in it is less secure. Add software to it, it gets even worse. By the way, I have the datasheet of the IC for car's infrared doorlocks. << post edited by berkeman >> Experimentally: before I drove twice to a non-disclosure industrial site, my car had been opened each time. Passenger doors which respond to an infrared key were opened. The boot (trunk) door, which needs a simple mechanical key, was not. Last edited by a moderator: Nov 11, 2008 12. Nov 11, 2008 ### berkeman ### Staff: Mentor Lets try to avoid posting things that will make it easier for folks to try out spoofing locks, okay? Sure, it's readily avaliable via google with the right search terms, but we're not going to allow it being posted directly here. Please be careful what links you post, and what you say about how to spoof different kinds of locks. Thanks. 13. Nov 11, 2008 ### Integral Staff Emeritus A place I used to work is now making "smart" locks. Some of you old timers may recognize the name, http://www.videx.com/CyberLock/Home.html" [Broken] from the Apple II days. Last edited by a moderator: May 3, 2017 14. Jul 14, 2009 ### JCOX This is why the hell we don't want key doors! Because crack heads don't know how to bump a Key card door! Oh yea and the problem with those damn key swipe things isn't the mechanical part ... its the magnetic reader. Oh yea ELECTRICAL ENGINEERS made those right? Last edited by a moderator: Sep 25, 2014 15. Jul 14, 2009 ### mgb_phys It's probably the fault of production engineers making them cheap! You normally use them indoors in areas that are already reasonably secure - like hotels or offices. The main requirement is for cheap. RFID keys are more reliable but cost$5 when you forgot to hand back your key card at the hotel instead of 25c for the magnetic ones.

16. Jul 14, 2009

### chayced

Magnetic swipe systems are pretty reliable. The problem with the hotel doors is because the cards are reused over and over again and the systems themselves are cheap. In comparison, how long does it take your ATM card to stop reading correctly? The best part about swipe systems is that you can lock out any one person's card without changing everyone's cards. The bad part is that just like metal keys they can be easily coppied with the right equipment.

No lock will ever be 100% reliable. If it can be opened with a key it can also be opened without the key.

17. Jul 14, 2009

### Proton Soup

not sure which i'd rather have, magnetic strip or RFID. the problem with RFID is that it broadcasts, so you could observe it from a distance. but the tech is not ubiquitous yet, so it'd take sophisticated criminals to break it. unless there's something i'm missing about how RFID works, i don't think moving to a more obscure technology makes me any more secure.

magnetic strips are ubiquitous and cheap to duplicate, but you need physical access to the card. maybe difficult with normal hotel door locks, but in general, trojan swipe readers are pretty common.

18. Jul 14, 2009

### mgb_phys

Depends on how secure the lock is !
Some RFID just send an ID number, most of them are very short range - ironically the cheaper/smaller they are the less sensitive the antennae and the shorter the range = more secure!
Key fobs for expensive cars and high security login keys for computers have a challenge-response system. The lock sends an encrypted message, the key manipulates that mathemetically and sends back a response, if that matches the same manipulation process in the lock it opens - a new message is generated each time and each response is different so recording them off the air isn't enough.

19. Jul 14, 2009

### chayced

RFID with a smart chip or a card with a smart chip are both great options because of the challenge/response involved, but they are expensive. I read a story, although it may just be an urban legend, about a guy that drove his new BMW to starbucks and sat reading the paper next to a kid with a laptop. After about 30 minutes the kid with the laptop got up and drove the BMW away. With any challenge/response system this is possible although the complexity of the system dictates the amount of time required to get a large enough pool of responses to trick it. Still better than a single code on a card or RFID.

In the end it's like the joke about the two guys being chased by the bear. You may not be able to create a perfectly secure system, but you can make the criminals go down the street to the system that is easer to crack.

20. Jul 14, 2009

### Staff: Mentor

Interesting info on lock bumping. I hadn't seen that before. I think stock in the MEDECO company just went up!

Last edited by a moderator: Sep 25, 2014