Complex regex password check

Question

I've a regex check for my email parameter, I want to implement regex check as well for password parameter.

For my email account I do something like this:

- (BOOL)isValidEmailAddress:(NSString*)emailAddressToCheck
{
    BOOL stricterFilter = YES;
    NSString *stricterFilterString = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    NSString *laxString = @".+@.+\\.[A-Za-z]{2}[A-Za-z]*";
    NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
    return [emailTest evaluateWithObject:emailAddressToCheck];
}

But I wonder how can I do it for password parameter check:

What I want to achieve is password with repeated character more than 3 times is not allowed.
1, 2, 3 OR 3, 2, 1 for example is not allowed.
Letters and numbers.

Any ideas how can I do that?

zx81 · Accepted Answer · 2014-05-12 07:59:15Z

Idan, as a regex lover, I really hate to say that something is not possible with regex. However, I don't think that the task you specified is a good task for regex. True, someone could conceivably find a way to hack a solution together, I've been blown away before. That being said, I have never seen a solution for point 2 below.

For instance, to check that each character, a for instance, occurs less than 3 times in the string, is quite challenging and probably involves an infinite-width lookaround, available only in .NET
Regex is of no use when it comes to checking random sequences such as abc, 123, 987
As I'm sure you're aware, number 3 is not a problem. In a unicode environment, where \d could stand for Arabic digits, you are better off sticking with specific character classes, such as [a-z0-9] in case-insensitive mode.

I would make separate methods for each criterion and forget about regex, except of course as a pre-filter for simpler conditions.

Collectives™ on Stack Overflow

Complex regex password check

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related