ASP.NET Identity, require ‘strong’ passwords

You can configure password requirements in App_Start\IdentityConfig.cs

// Configure validation logic for passwords
manager.PasswordValidator = new PasswordValidator
{
    RequiredLength = 4,
    RequireNonLetterOrDigit = false,
    RequireDigit = false,
    RequireLowercase = false,
    RequireUppercase = false,
};