Hardware-based security keypad keeps it simple

hardware_keypad_lock

Instructables user [trumpkin] recently built an all-hardware based keypad lock for a contest he was entering, and we thought it was pretty neat. The lock uses mostly NAND gates and 555 timers to get the job done, which makes it a nice alternative to similar software-based projects we have seen in the past.

The lock has 6 keys on the keypad, which is connected to the main logic board. The keycode is set using a series of headers at the bottom of the board, and you get 10 chances to enter the proper code before the board locks up completely. If this occurs, a “manual” reset via a button built into the main board is required before any more attempts can be made.

As you can see in the video below, the lock works quite well, but suffers from one shortcoming. Any permutation of the key code can be used to deactivate the lock, which is something [trumpkin] says he would like to improve in the future.

If you are looking for some more security-related reading, be sure to check out these other hacks we have featured in the past.

Comments

  1. biozz says:

    simple and huge XD

    and probably easier to tamper XD

  2. I once designed a reprogrammable sequential combination lock using RS Nor Latches and AND gates. Problem is, when i put it into a simulator the diodes all blew :{
    Another big problem was that there was no failure condition.

  3. alan says:

    Could the author please define “simple”?

  4. bogdan says:

    you can make a code lock using a simple counter, like the 4017 that is already used in the schematic. It is very simple. I think the original design comes from Elektor. At least that is where I’ve built it from a long time ago.
    I’ve managed to find what seems like the original schematic here http://www.scribd.com/doc/51140395/Simple-ic-projects under ‘security door key 1′.

  5. Ha'KoTH says:

    “Any permutation of the key code”? I assume you mean any “n-permutation of the key code of length n”. Otherwise, there wouldn’t be all that much security here whatsoever…

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 96,711 other followers