How to Customize Password Policy in ASP.Net Identity

By default, ASP.NET MVC Identity requires a minimum password length of 6 characters and here we change it. To do that you need to create a CustomPasswordValidator class, then implement the IIdentityValidator interface.

public class CustomPasswordValidator : IIdentityValidator<string>
{
    public int RequiredLength { get; set; }
    public CustomPasswordValidator(int length) {
        RequiredLength = length;
    }
    public Task<IdentityResult> ValidateAsync(string password) {
        if (String.IsNullOrEmpty(password) || password.Length < RequiredLength)
        {
            return Task.FromResult(IdentityResult.Failed(
                String.Format("Password should be at least {0} characters", RequiredLength)));
        }
        int counter = 0;
        List<string> patterns = new List<string>();
        patterns.Add(@"[a-z]");                                          // lowercase
        patterns.Add(@"[A-Z]");                                          // uppercase
        patterns.Add(@"[0-9]");                                          // digits
        patterns.Add(@"[!@#$%^&*\(\)_\+\-\={}<>,\.\|""'~`:;\\?\/\[\]]"); // special symbols
        //check patterns
        foreach (string p in patterns)
        {
            if (Regex.IsMatch(password, p))
                counter++;
        }
        if (counter < 2)
        {
            return Task.FromResult(IdentityResult.Failed(
                "Please enter your password at least two lowercase letters, uppercase letters, number letters and special symbols."));
        }
        return Task.FromResult(IdentityResult.Success);
    }
}

You can use Regex to check your pattern. The Regex class represents the regular expression engine of the .NET Framework. It can be used to quickly parse large amounts of text to find specific character patterns to extract, edit, replace or delete text substrings.

Open the IdentityConfig.cs the modify PasswordValidator as shown below

manager.PasswordValidator = new CustomPasswordValidator(7);