0
$\begingroup$

How do I calculate the password space of a randomized linked hybrid pasword of 9 images and 10 numbers(0-9)? User allowed to select 4 password

Images=9 Pin= 0-9 Password selection allowed: 4 Every image is linked to a number

Images are randomized at each selection

Improve this question
$\endgroup$
5
  • 1
    $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Nov 18, 2022 at 7:01
  • $\begingroup$ I am trying to calculate the password space for a graphical password of 9images each image is linked to a number from 0-9.. and users are allowed to select just 4 images $\endgroup$
    – Gloria Jiya
    Nov 18, 2022 at 7:20
  • $\begingroup$ The answer is 9-choose-4 I think. $\endgroup$
    – tur11ng
    Nov 18, 2022 at 9:45
  • $\begingroup$ @GloriaJiya So you want to know the keyspace when you have 10 images (images numbered 0 through 9 would total 10 images, not 9) to choose from, and four are picked at random. Is that correct? $\endgroup$
    – forest ♦
    Nov 18, 2022 at 22:39
  • $\begingroup$ @forest yes that is correct. $\endgroup$
    – Gloria Jiya
    Nov 19, 2022 at 0:02

1 Answer 1

Reset to default
1
$\begingroup$

The fact that a password is composed of images is irrelevant. If you have 10 possible values for each symbol and choose 4 symbols at random, the keyspace is 104 = 10000, and log2(10000) ≈ 13.3 bits.

This is very insecure!

In general, you can calculate the keyspace by raising the number of possible symbols to the number of randomly-selected symbols. This tells you how many possible combinations there are. You convert this number into the number of bits of security by taking the base-2 logarithm of the result.

For example, if you are choosing a password composed of 12 words chosen at random from a set of 4000, the number of bits of security is log2(400012) ≈ 145 bits, which is secure.

Improve this answer
$\endgroup$
5
  • $\begingroup$ Ok, for hybrid password password that has a password space for 1st step authentication of 10,000 and 2nd step authentication of 6,000. Do we add 10,000 to 6,000 or multiply 10,000 by 6,000. $\endgroup$
    – Gloria Jiya
    Nov 20, 2022 at 5:31
  • $\begingroup$ @GloriaJiya Will the attacker know if they got the first password correct before they try the second? $\endgroup$
    – forest ♦
    Nov 20, 2022 at 22:29
  • $\begingroup$ aforest yes the attacker will know. $\endgroup$
    – Gloria Jiya
    Nov 21, 2022 at 10:26
  • $\begingroup$ @GloriaJiya In that case, treat it like two separate passwords. First one is broken and then the other, so you aren't adding very much security by using two. $\endgroup$
    – forest ♦
    Nov 23, 2022 at 22:08
  • $\begingroup$ Okay thank you for the response. $\endgroup$
    – Gloria Jiya
    Dec 15, 2022 at 8:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.