Use only 3 unique digits in a 4-digit PIN for more security
Security expert, Karl Sigler, presents an interesting look into what a potential attacker sees and how math is on their side when a user uses 4 unique digits. In his article, Sigler points out that the residue from our fingers often leaves visible traces on the glass that narrows down the digits used in the PIN.
When changing that PIN to repeat one number, so for example let’s say the smudge marks on the phone are over 6, 8, and 9, the attacker now needs to determine which number is the one that repeats. This small change now makes the number of possible PINs rise to 36, which is a 50% improvement in security of a unique 4-digit PIN.
While this won’t protect you in a case of theft, it may buy you some time in a case when a nosey coworker, friend, or family member attempts to brute force into your phone while you step away for a few minutes.
source: Skeleton Key Security via Geek
3. The_Miz (Posts: 1496; Member since: 06 Apr 2011)
How dare you. Only I get to say First! + comment.
2. brenner182 (Posts: 29; Member since: 07 Dec 2011)
^ yep. biggest d**k ever now that you got first.
4. ardent1 (Posts: 1862; 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.
5. ardent1 (Posts: 1862; 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.
6. thelegend6657 (unregistered)
I hate Maths
8. Paden (Posts: 262; Member since: 07 Jul 2011)
Good thinking. Also, setting it to delete after 10 attempts helps too!