Regex for checking that at least 3 of 4 different character groups exist

Question

I'm trying to write a password validator.

How can I see if my supplied string contains at least 3 different character groups?

It's easy enough to check if they are existant or not ---but at least 3?

• at least eight (8) characters

• At least three different character groups

  upper-case letter

  lower-case letter

  numeric

  special characters !@#$%&/=?_.,:;-\

(I'm using javascript for regex)

Answer 1

Just to learn - would this kind of requirement be possible to implement in pure regex?

That'd make it a rather hard to read (and therefor maintain!) solution, but here it is:

(?mx)
^
(
  (?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])                # must contain a-z, A-Z and 0-9
  |                                                # OR
  (?=.*[a-z])(?=.*[A-Z])(?=.*[!@\#$%&/=?_.,:;\\-]) # must contain a-z, A-Z and special
  |                                                # OR
  (?=.*[a-z])(?=.*[0-9])(?=.*[!@\#$%&/=?_.,:;\\-]) # must contain a-z, 0-9 and special
  |                                                # OR
  (?=.*[A-Z])(?=.*[0-9])(?=.*[!@\#$%&/=?_.,:;\\-]) # must contain A-Z, 0-9 and special
)
.{8,}                                              # at least 8 chars
$

A (horrible) Javascript demo:

var pw = "aa$aa1aa";
if(pw.match(/^((?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])|(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#$%&\/=?_.,:;\\-])|(?=.*[a-z])(?=.*[0-9])(?=.*[!@#$%&\/=?_.,:;\\-])|(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#$%&\/=?_.,:;\\-])).{8,}$/)) {
  print('Okay!');
} else {
  print('Fail...');
}

prints: Okay!, as you can see on Ideone.

Answer 2

May as well join in on the fun:

String.prototype.isValidPW = function(){   
    // First, check for at least 8 characters
    if (this.length < 8) return false;

    // next, check that we have at least 3 matches
    var re = [/\d/, /[A-Z]/, /[a-z]/, /[!@#$%&\/=?_.,:;-]/], m = 0;
    for (var r = 0; r < re.length; r++){
        if ((this.match(re[r]) || []).length > 0) m++;
    }

    return m >= 3;
};

if ("P@ssW0rd".isValidPW()) alert('Acceptable!');

Demo