Password regex C#
Password regular expression can be used to verify that a password provided is strong enough to provide better protection against bot brute force attacks. This method, however, does not guarantee that a password will have enough entropy to be completely safe.
Strong password regex
The regular expression below cheks that a password:
- Has minimum 8 characters in length. Adjust it by modifying {8,}
- At least one uppercase English letter. You can remove this condition by removing (?=.*?[A-Z])
- At least one lowercase English letter. You can remove this condition by removing (?=.*?[a-z])
- At least one digit. You can remove this condition by removing (?=.*?[0-9])
- At least one special character, You can remove this condition by removing (?=.*?[#?!@$%^&*-])
new Regex("^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$")
Enter a text in the input above to see the result
Example code in C#:
using System.Text.RegularExpressions;
using System;
public class Program
{
public static void Main()
{
// Validate strong password
Regex validateGuidRegex = new Regex("^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$");
Console.WriteLine(validateGuidRegex.IsMatch("-Secr3t.")); // prints True
}
}
Notes on password regex validation
While this regex validation is better than nothing, in situations when additional security is needed you should also check the password entered for a set of commonly used passwords like:
- .Qwerty1
- !Q1w2e3r4
- etc
One good list can be found here.
