Regex to validate passwords with characters restrictions

Question

I need to validate a password with these rules:

• 6 to 20 characters
• Must contain at least one digit;
• Must contain at least one letter (case insensitive);
• Can contain the following characters: ! @ # $ % & *

The following expression matches all but the last requirement. What can I do with the last one?

((?=.*\d)(?=.*[A-z]).{6,20})

Answer 1

I'm not completely sure I have this right, but since your last requirement is "Can contain the following characters: !@#$%&*" I am assuming that other special characters are not allowed. In other words, the only allowed characters are letters, digits, and the special characters !@#$%&*.

If this is the correct interpretation, the following regex should work:

^((?=.*\d)(?=.*[a-zA-Z])[a-zA-Z0-9!@#$%&*]{6,20})$

Note that I changed your character class [A-z] to [a-zA-Z], because [A-z] will also include the following characters: [\]^_`

I also added beginning and end of string anchors to make sure you don't get a partial match.