![[image of code keypad]](https://blogs.kcl.ac.uk/proged/wp-content/blogs.dir/192/files/2010/06/keypad.jpg)
A security access keypad
Here is an image of a security access keypad. It controls access to a private parking area at the back of my house.
Maybe not quite as secure as intended…
Security and unintended leakage of information
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4! combinations means up to 24 tries. If that lock is worth it’s money, there’s a timedelay as soon as a wrong code is entered 3 times in a line.
this is why, when typing a windows password, the third or fourth subsequent wrong password has a long delay where it “tries” to login (with the aero “hour glass circle”) but still returns a failure at the end.
Information leakage indeed. I think I figured out someones birth year.
4! would be 4 factorial, or 4x3x2x1. I don’t think that that is an accurate assessment. First you would have to know that it only uses 4 digits, it is possible that the code is 8 digits, but they are used multiple times. I think an accurate assessment would be 4x4x4x4 if it is indeed limited to a length of 4 digits. It would grow exponentially larger as you added digits though. It surely isn’t secure, and maintained by a lazy person who has decided not to use a revolving password or a rag/cleaner. : (
My guess is that the combination is 1953 – humans are so pathetic at choosing random numeric digits, and tend to go with things like the year of their birth.
If it’s a 4 cipher coder, there’s only 10 options (since we know that four keys are used)
I bet it’s either 1593, 3159, 9513 or 3951, since most people organize it as a pattern…
#6 – how are there only 10 options? I’m assuming only 4 keys, and I make 24 options…
Well, assuming 4 keys in a password, and a total 4 keys pressed, each key is only used once.
1359
1395
1539
1593
1935
1953
3159
3195
3519
3591
3915
3951
5139
5193
5319
5391
5913
5931
9135
9153
9315
9351
9513
9531
Yup, 24,
@simon
Assuming 1 4-digit-long passcode, each digit must be used once. So combinations like 3359 with repeated digits are out.
Those are a lot of assumptions. You can’t assume it’s 4 digits or that repeating digits isn’t allowed. That blows your theory of 24 possibilities out of the water. Although looking up the manual for this device could shed some light for you noobs.
This makes for quite a good math lesson 🙂
See http://blog.mrmeyer.com/?p=3675
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