regular expression for password with few rules

Question

I want a function checkPassword function, which should check if the password parameter adheres to the following rules:

Must be longer than 6 characters
Allowed characters are lower or upper case Latin alphabet characters (a-z), numbers (0-9), and special characters +, $, #, \, / only
Must not have 3 or more consecutive numbers (e.g. "pass12p" is fine, but "pass125p" is not, because it contains "125")

checkPassword should print "true" to the console if the password parameter adheres to the said rules, and "false" if it does not.

What have you tried? And there are plenty of online checkers to test things out...http://www.regexr.com/ is one of my faves — Scott Mitchell, Aug 10 '14 at 15:45
You can use something like this: `([\w+$#/\\]){6,}` but doesn't fix point 3 — Federico Piazza, Aug 10 '14 at 16:03
@theftprevention yes but that easily is solved to `([a-zA-Z\d$#/\\]){6,}` I just wanted to provide an option to OP — Federico Piazza, Aug 10 '14 at 16:10

Federico Piazza · Accepted Answer · 2014-08-13T22:29:58.107

3

You can use the following regex and get the content of the capturing group to check if your string is valid:

.*\d{3}.*|^([\w\+$#/\\]{6,})$

Working demo

Using \w allows A-Za-z0-9_ if you don't want underscore on your regex you have to replace \w by A-Za-z0-9

For the following examples:

pass12p            --> Pass
pass125p           --> Won't pass
asdfasf12asdf34    --> Pass
asdfasf12345asdf34 --> Won't pass

Match information is:

MATCH 1
1.  `pass12p`
MATCH 2
1.  `asdfasf12asdf34`

edited Aug 13 '14 at 22:29

answered Aug 10 '14 at 16:31

Federico Piazza

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This is pretty clever, well done! I couldn't think of a way to do it with a single regex. – theftprevention Aug 10 '14 at 17:49
@theftprevention thank, glad you like it. That regex technique is very useful – Federico Piazza Aug 10 '14 at 18:05
@theftprevention I answered a question showing this more graphicaly, if you want you can take a look at here: http://stackoverflow.com/questions/25190108/getting-a-look-behind-to-look-back-as-many-characters-as-necessary/25190225#25190225 – Federico Piazza Aug 10 '14 at 18:07
-1 Your regex would validate e.g. `'abc27d££'` as you haven't anchored it with `^` and `$`. – MikeM Aug 13 '14 at 21:27
@MikeM that caracter is not asked by OP. Don't downvote without reason – Federico Piazza Aug 13 '14 at 22:12

score 0 · Answer 2 · answered Aug 10 '14 at 16:05

The best way would be to use two separate regular expressions. First, make sure the password matches this first one, which checks for adherence to rules #1 and #2:

[A-Za-z0-9#$\/\\\+]{6,}

Then, make sure the password does not match this second regular expression, which checks for the presence of a sequence of 3 consecutive numbers anywhere in the password:

\d{3}

MikeM · Answer 3 · 2014-08-10T17:28:07.613

-1

function checkPassword(str) {
  console.log( /^(?!.*\d{3})[+a-z\d$#\\/]{6,}$/i.test(str) );
}

edited Aug 10 '14 at 17:28

answered Aug 10 '14 at 17:16

MikeM

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regular expression for password with few rules

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