Template implementation of a custom ASP.NET MembershipProvider, using C#.

CustomMembershipProvider.cs

using System;
using System.Collections.Specialized;
using System.Configuration.Provider;
using System.Web.Configuration;
using System.Web.Security;

namespace Custom.Providers
{
	public class CustomMembershipProvider : MembershipProvider
	{
		private string _applicationName, _passwordStrengthRegularExpression, _connectionString;
		private bool _requiresUniqueEmail,  _requiresQuestionAndAnswer, _enablePasswordRetrieval, _enablePasswordReset;
		private int _passwordAttemptWindow, _minRequiredPasswordLength, _minRequiredNonAlphanumericCharacters, _maxInvalidPasswordAttempts;

		private MachineKeySection _machineKey; //Used when determining encryption key values.
		private MembershipPasswordFormat _passwordFormat = MembershipPasswordFormat.Hashed;


		public override string ApplicationName
		{
			get
			{
				return _applicationName;
			}
			set
			{
				_applicationName = value;
			}
		}

		public override int MaxInvalidPasswordAttempts
		{
			get { return _maxInvalidPasswordAttempts; }
		}

		public override int MinRequiredNonAlphanumericCharacters
		{
			get { return _minRequiredNonAlphanumericCharacters; }
		}

		public override int MinRequiredPasswordLength
		{
			get { return _minRequiredPasswordLength; }
		}

		public override int PasswordAttemptWindow
		{
			get { return _passwordAttemptWindow; }
		}

		public override MembershipPasswordFormat PasswordFormat
		{
			get { return _passwordFormat; }
		}

		public override string PasswordStrengthRegularExpression
		{
			get { return _passwordStrengthRegularExpression; }
		}

		public override bool RequiresQuestionAndAnswer
		{
			get { return _requiresQuestionAndAnswer; }
		}

		public override bool RequiresUniqueEmail
		{
			get { return _requiresUniqueEmail; }
		}

		public override bool EnablePasswordReset
		{
			get { return _enablePasswordReset; }
		}

		public override bool EnablePasswordRetrieval
		{
			get { return _enablePasswordRetrieval; }
		}

		public override bool ChangePassword( string username, string oldPassword, string newPassword )
		{
			throw new NotImplementedException();
		}

		public override bool ChangePasswordQuestionAndAnswer( string username, string password, string newPasswordQuestion, string newPasswordAnswer )
		{
			throw new NotImplementedException();
		}

		public override MembershipUser CreateUser( string username, string password, string email, string passwordQuestion, string passwordAnswer, bool isApproved, object providerUserKey, out MembershipCreateStatus status )
		{
			throw new NotImplementedException();
		}

		public override bool DeleteUser( string username, bool deleteAllRelatedData )
		{
			throw new NotImplementedException();
		}

		public override MembershipUserCollection FindUsersByEmail( string emailToMatch, int pageIndex, int pageSize, out int totalRecords )
		{
			throw new NotImplementedException();
		}

		public override MembershipUserCollection FindUsersByName( string usernameToMatch, int pageIndex, int pageSize, out int totalRecords )
		{
			throw new NotImplementedException();
		}

		public override MembershipUserCollection GetAllUsers( int pageIndex, int pageSize, out int totalRecords )
		{
			throw new NotImplementedException();
		}

		public override int GetNumberOfUsersOnline()
		{
			throw new NotImplementedException();
		}

		public override string GetPassword( string username, string answer )
		{
			throw new NotImplementedException();
		}

		public override MembershipUser GetUser( string username, bool userIsOnline )
		{
			throw new NotImplementedException();
		}

		public override MembershipUser GetUser( object providerUserKey, bool userIsOnline )
		{
			throw new NotImplementedException();
		}

		public override string GetUserNameByEmail( string email )
		{
			throw new NotImplementedException();
		}

		public override string ResetPassword( string username, string answer )
		{
			throw new NotImplementedException();
		}

		public override bool UnlockUser( string userName )
		{
			throw new NotImplementedException();
		}

		public override void UpdateUser( MembershipUser user )
		{
			throw new NotImplementedException();
		}

		public override bool ValidateUser( string username, string password )
		{
			throw new NotImplementedException(); // NOTE: should implement this
		}

		
		public override void Initialize(string name, NameValueCollection config)
		{
			if (config == null)
			{
				throw new ArgumentNullException("config");
			}

			if (name == null || name.Length == 0)
			{
                name = "CustomMembershipProvider";
			}

			if (String.IsNullOrEmpty(config["description"]))
			{
				config.Remove("description");
				config.Add("description", "Custom MembershipProvider");
			}

			// Initialize the abstract base class.
			base.Initialize(name, config);

			_applicationName = GetConfigValue(config, "applicationName", System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath);
			_maxInvalidPasswordAttempts = Convert.ToInt32(GetConfigValue(config, "maxInvalidPasswordAttempts", "5"));
			_passwordAttemptWindow = Convert.ToInt32(GetConfigValue(config, "passwordAttemptWindow", "10"));
			_minRequiredNonAlphanumericCharacters = Convert.ToInt32(GetConfigValue(config, "minRequiredAlphaNumericCharacters", "1"));
			_minRequiredPasswordLength = Convert.ToInt32(GetConfigValue(config, "minRequiredPasswordLength", "7"));
			_passwordStrengthRegularExpression = Convert.ToString(GetConfigValue(config, "passwordStrengthRegularExpression", String.Empty));
			_enablePasswordReset = Convert.ToBoolean(GetConfigValue(config, "enablePasswordReset", "true"));
			_enablePasswordRetrieval = Convert.ToBoolean(GetConfigValue(config, "enablePasswordRetrieval", "true"));
			_requiresQuestionAndAnswer = Convert.ToBoolean(GetConfigValue(config, "requiresQuestionAndAnswer", "false"));
			_requiresUniqueEmail = Convert.ToBoolean(GetConfigValue(config, "requiresUniqueEmail", "true"));

			string temp_format = config["passwordFormat"];
			if (temp_format == null)
			{
				temp_format = "Hashed";
			}

			switch (temp_format)
			{
				case "Hashed":
					_passwordFormat = MembershipPasswordFormat.Hashed;
					break;
				case "Encrypted":
					_passwordFormat = MembershipPasswordFormat.Encrypted;
					break;
				case "Clear":
					_passwordFormat = MembershipPasswordFormat.Clear;
					break;
				default:
					throw new ProviderException("Password format not supported.");
			}

			var ConnectionStringSettings = WebConfigurationManager.ConnectionStrings[config["connectionStringName"]];

			if ((ConnectionStringSettings == null) || (string.IsNullOrWhiteSpace(ConnectionStringSettings.ConnectionString.Trim())))
			{
				throw new ProviderException("Connection string cannot be blank.");
			}

			_connectionString = ConnectionStringSettings.ConnectionString;

			//  Get encryption and decryption key information from the configuration.
			var cfg = WebConfigurationManager.OpenWebConfiguration(System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath);
			_machineKey = cfg.GetSection("system.web/machineKey") as MachineKeySection;

			if (_machineKey.ValidationKey.Contains("AutoGenerate"))
			{
				if (PasswordFormat != MembershipPasswordFormat.Clear)
				{
					throw new ProviderException("Hashed or encrypted passwords are not supported with auto-generated keys.");
				}
			}
		}


		private string GetConfigValue(NameValueCollection configuration, string key, string defaultValue)
		{
			if (configuration == null || String.IsNullOrEmpty(key))
			{
				return defaultValue;
			}

			return configuration[key];
		}
	}
}