Validate that password doesn't contain 3+ consecutive characters from name

Question

I need to do this following password validation in Java

• Must be at least 8 characters in length
• Must contain at least 1 number
• Must contain at least 1 upper case letter
• Must contain at least 1 lower case letter
• Cannot contain 3 or more consecutive characters from your full name or your username (e.g. If your name is Will you couldn't have the password Stiller458)

I have the first 4 points, how do I do the last one?

Currently I have:

String pattern = "^(?=.*[^a-zA-Z])(?=.*[a-z])(?=.*[A-Z])\\S{8,}$";
boolean passwordValidation = originalPassword.matches(pattern);

Solution 1

For your 1,2,3,4 case

^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])[a-zA-Z\d]{8,}$

For your 5th case

public boolean isValid(final String userName,final String password)
{
    for(int i=0;(i+2)<userName.length();i++)
          if(password.indexof(userName.substring(i,i+2))!=-1)
                return false;
    return true;
}

Solution 2

The last point is not something you do with regex. Loop through the name and check against the password instead.

Regex is good at patterns, not parsing. One way or another you have to use a loop to go through the name.

Comments

[Vivek]

I am getting an "java.lang.StringIndexOutOfBoundsException: String index out of range: 8", any idea why?

[Anirudha]

@Vivek oops..check out the edit now..instead of using userName.length() i used password.length()..small error

[Vivek]

Tnx, also I changed if(password.indexof(userName.substring(i,i+2))!=-1) to if(password.indexOf(userName.substring(i,i+3))!=-1) to cater to contains 3 or more

[Anirudha]

@Vivek checking for 3 is as good as checking for 4,5,6,7,.... so you only need to check for 3 characters..