Umbraco - set strong password policy

UmbracoCustomOwinStartup.cs

using Microsoft.Owin;
using Owin;
using Umbraco.Core;
using Umbraco.Core.Security;
using Umbraco.Web.Security.Identity;
using Umbraco.Core.Models.Identity;
using Website.Web;
using Umbraco.Web;

//To use this startup class, change the appSetting value in the web.config called 
// "owin:appStartup" to be "UmbracoCustomOwinStartup"

[assembly: OwinStartup("UmbracoCustomOwinStartup", typeof(UmbracoCustomOwinStartup))]

namespace Website.Web
{
    /// <summary>
    /// A custom way to configure OWIN for Umbraco
    /// </summary>
    /// <remarks>
    /// The startup type is specified in appSettings under owin:appStartup - change it to "UmbracoCustomOwinStartup" to use this class
    /// 
    /// This startup class would allow you to customize the Identity IUserStore and/or IUserManager for the Umbraco Backoffice
    /// </remarks>
    public class UmbracoCustomOwinStartup : UmbracoDefaultOwinStartup
    {
        public new void Configuration(IAppBuilder app)
        {
            app.SanitizeThreadCulture();
            this.ConfigureServices(app);
            this.ConfigureMiddleware(app);
        }

        /// <summary>
        /// Configures services to be created in the OWIN context (CreatePerOwinContext).
        /// </summary>
        /// <param name="app"></param>
        protected new void ConfigureServices(IAppBuilder app)
        {
            app.SetUmbracoLoggerFactory();
            this.ConfigureUmbracoUserManager(app);
        }

        /// <summary>
        /// Configure the Identity user manager for use with Umbraco Back office.
        /// Additionaly also sets stronger password requirements.
        /// </summary>
        protected new void ConfigureUmbracoUserManager(IAppBuilder app)
        {
            var applicationContext = ApplicationContext.Current;

            app.ConfigureUserManagerForUmbracoBackOffice<BackOfficeUserManager, BackOfficeIdentityUser>(
                applicationContext,
                (options, context) =>
                {
                    var membershipProvider = MembershipProviderExtensions
                        .GetUsersMembershipProvider()
                        .AsUmbracoMembershipProvider();
                    var settingContent = Umbraco.Core.Configuration.UmbracoConfig.For.UmbracoSettings().Content;
                    var userManager = BackOfficeUserManager.Create(options,
                        applicationContext.Services.UserService,
                        applicationContext.Services.EntityService,
                        applicationContext.Services.ExternalLoginService,
                        membershipProvider,
                        settingContent);

                    SetPasswordRequirements(userManager);

                    return userManager;
                });

        }

        private void SetPasswordRequirements(BackOfficeUserManager backOfficeUserManager)
        {
            // If this doesn't work we want to fail hard.
            var membershipProviderPasswordValidator = (MembershipProviderPasswordValidator)backOfficeUserManager.PasswordValidator;

            // Set strong password policy.
            membershipProviderPasswordValidator.RequireDigit = true;
            membershipProviderPasswordValidator.RequireLowercase = true;
            membershipProviderPasswordValidator.RequireNonLetterOrDigit = true;
            membershipProviderPasswordValidator.RequireUppercase = true;
            membershipProviderPasswordValidator.RequiredLength = 9;
        }
    }
}