Revision as of 13:53, 25 September 2008

Entry Automation

General Implementation Notes

• The system needs to be powered, and preferably include a UPS
• Overriding key access is nice for graceful failure
  • Of course, this just underlines the fact that this is an access registry system more than anything
• Probably need a normal handle in the door with an electric door strike for the cheapest implementation.
• If the implementation simply replaces the metal key with a token, it will have the same problems. Unless two- or three-factor authentication is used and/or the physical security of the lock and door are improved, it's about as secure as it was.
• Simple enough to manage the coming and going of people.

RFID

Pros

• Hands-off access
• Hands-off tracking of access
  • As long as user has their RFID tag on them, their presence within a certain proximity around the reader will be recorded.

Cons

• Keys easily stolen with anonymity
• Your tracking me!

Implementation

Materials

• Need a reader with good range. Can be found for under $100
• To build a system that can perform coming/going detection, would need two readers. or 1 + N readers, where N is the number of approachable directions
• Need a writer. Under $100
  • Some writers are substantially more expensive. Q: Why the price difference?
• Need a server

iButton

Pros

• Rotating keys are available
• Someone must have physical access to the fob to capture the non-rotating key

Cons

• Hands-on access
• 1 wire interface may be fakable with any interface that has the same signal levels (very cheap and easy buttonforging)
  • prove it --strages 20:18, 8 May 2008 (CDT)
    • iButton Spoofing. I'm not promising to get around to this anytime soon, but I'll layout how to spoof the static key iButton here. Omegix 23:02, 8 May 2008 (CDT)
  • It doesn't matter. Old keys are still eliminated from the system. And the threat of theft through kicking the door in is much higher than copying a valid key. --Korc 20:51, 8 May 2008 (CDT)
• User may forget to log their entry to the area.
  • If door is open, no incentive to use key
  • Group of people walk in at once
  • Someone knocks and has the door opened for them
  • All these Cons are valid for any system --Korc 19:26, 8 May 2008 (CDT)
    • True, but not so much with RFID. With RFID as long as the person has their tag on them, simply walking within a few feet of the reader will activate it. Most people are used to RFID readers with short reading distances, ones with longer throws are found at storage units so that people don't have to get out of their cars. There's a cheap long throw reader on ebay that can do 40 meters. Of course, if people don't keep their RFID tag/card on their person, then that screws the pooch. Omegix 23:07, 8 May 2008 (CDT)
    • This point makes no sense! Why do we need a long range reader? Why do we need to track people once they are at the shop? If you have a long range reader, won't this make it harder to track coming and going of people? The hole purpose of access control is to first control access to "users" and second keep track of people coming and going. Getting a long range reader so you can be lazy and not have to hold up your card is rather stupid, because now if I even get close to the reader, its tagged me as coming or going. Unless of course you just track everyone in the vicinity, but I'm guessing that will be harder to do, cost more...and frankly I don't want you to track me with RFID. With the iButton you simple touch it to a pad, stating you have either entered or exited for the day. If you don't, you won't get credit for being there...seems simple enough to me--JimShoe 10:24, 9 May 2008 (CDT)

USB Authentication

Pros

Each USB device has a unique serial ID. USB keys are cheap, readily available, and many can fit on a standard metal keyring.

Cons

Implementation

Authentication Flow

1. User inserts key into USB hub hooked to a PC
2. Computer reads serial ID of key
3. Computer compares serial ID to list of valid serial ID in a table \ DB \ Flat File
4. If good, computer writes data ("Unlock!") to USB line of Microcontroller
5. Microcontroller throws a pin high for 5-10 seconds.
6. Pin is likely 3-5volts. Pin is wired to either a 200ma transistor or relay
7. Relay, when thrown, sends 12V of 200mA current to an electric doorstrike

Useful Microcontroller (Arduino/Freeduino) Resources

• Writing to Serial
• More Serial
• ASCII Table Info
• No really, this serial right here

Suggested Implementation Phases

1. Get microcontroller to throw a pin high
2. Get microntroller to read commands issued from external system (serial/USB)
3. Get microcontroller to throw Pin high after recieving external command
4. Build and test simple door strike circuit