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Use only 3 unique digits in a 4-digit PIN for more security

0. phoneArena 02 Jan 2012, 14:21 posted on

Many people claim that eyes are the window to the soul, but we’d be willing to bet that you can find out a lot more about a person by accessing their smartphone. That is precisely why more and more people are using access codes to lock their devices from prying hands. When it comes to setting a code, what is the best way to go about it? Interestingly enough, in this case, less is more.

This is a discussion for a news. To read the whole news, click here

posted on 02 Jan 2012, 14:30 1

1. m.garz (Posts: 61; Member since: 08 Oct 2010)


first! :D

posted on 02 Jan 2012, 15:02 6

3. The_Miz (Posts: 1496; Member since: 06 Apr 2011)


How dare you. Only I get to say First! + comment.

posted on 02 Jan 2012, 14:43 3

2. brenner182 (Posts: 29; Member since: 07 Dec 2011)


^ yep. biggest d**k ever now that you got first.

posted on 02 Jan 2012, 15:35 3

4. ardent1 (Posts: 1997; Member since: 16 Apr 2011)


24 combinations is due to 4 choices for the first number, 3 choices for the second, 2 choices for the third number and one choice for the last number or 4*3*2*1 = 24.

Okay, I read the solution online since order matters. The correct answer is 12 if you don't assume symmetry and 36 if you assume symmetry.

posted on 02 Jan 2012, 15:58 2

5. ardent1 (Posts: 1997; Member since: 16 Apr 2011)


Okay, since the order of the numbers matter, it's a permutation problem and not combinations. I read the solution online and the answer is 12 if you reject the symmetry argument or 36 if you accept the symmetry argument.

The symmetry assumption is that ALL THREE inputs leave the same marks. However, if you leave a BIGGER spot for the duplicate digit, your password is 50% weaker than a non-repeat 4 digit code.

posted on 02 Jan 2012, 18:19 3

6. thelegend6657 (unregistered)


I hate Maths

posted on 03 Jan 2012, 09:04

7. Synack (Posts: 668; Member since: 05 Jul 2011)


what if you only use 2 numbers???

posted on 03 Jan 2012, 19:29

8. Paden (Posts: 262; Member since: 07 Jul 2011)


Good thinking. Also, setting it to delete after 10 attempts helps too!

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