This post shows how to configure a require strong password in ASP.NET Identity using C#.NET.

Open your IdentityConfig.cs class

manager.PasswordValidator = new PasswordValidator
    RequiredLength = 6, // Minimum length of the password
    RequireNonLetterOrDigit = true, // Must include a special character
    RequireDigit = true, // Must include a number
    RequireLowercase = true, // Must include a lowercase character
    RequireUppercase = true // Must include an uppercase character

Use the PasswordValidator properties to define your own password validation policy.