If I'm using 16-18 character-length passwords with 94 different possible values-per-character (lower alphas, upper alphas, numbers, and special characters), is there an equation I can use to calculate how many times a series of the same value will be presented?
What I'm trying to find out is with granular password complexity programs, you can specify the max number of characters that can be seen adjacent to each other before they are discarded. What I want to know is, if a low value (e.g. 2) is used, how severly does this impact the key space for resistence against brute force attacks.
As in, in a 16 character password's keyspace of 94^16, if the number of same-values can't be 2 or more, how many possible passwords are removed from the available passwords an attacker has to use?
e.g. in the case of 2 same-value characters, the following passwords would be rejected:
- 12345667890abcdefgWW - because of the 66 and WW
- sadfl;jkxz089--qwer - because of the --
- a;lksdjf%%;slkdaj;;zlc - because of the %% and ;;
- 2134@!#$SAf;ljkasdf$$$$cQ - because of the $$$$
...is there an equation to perform this type of calculation?