CredentialsManager

// Saving credentials into Windows credentials storage

// Helper class for CredentialManagement library (http://www.nuget.org/packages/CredentialManagement/)
// It loads the library dynamically, so you can add or remove it at runtime

using System;
using System.IO;
using System.Linq;
using System.Reflection;

namespace MyApp.Credentials
{
    static class CredentialsManager
    {
        private const string TARGET_PREFIX = "MyApp@";
        private const string CREDENTIAL_LIBRARY_NAME = "CredentialManagement";
        private static readonly string PATH_TO_EXECUTION_FOLDER = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
        private static readonly string PATH_TO_DLL = Path.Combine(PATH_TO_EXECUTION_FOLDER, CREDENTIAL_LIBRARY_NAME + ".dll");

        private static bool _alreadyTriedLoadCredentialLibrary;


        public static bool IsCredentialsLibraryLoaded
        {
            get { return getCredentialLibrary() != null; }
        }

        public static bool StoreCredentials(UserCredentials user)
        {
            try
            {
                var asm = getCredentialLibrary();
                if (asm == null)
                    return false;

                var credentialType = asm.GetType("CredentialManagement.Credential");
                var persistanceEnumType = asm.GetType("CredentialManagement.PersistanceType");
                
                dynamic cm = Activator.CreateInstance(credentialType);
                cm.Target = TARGET_PREFIX + user.Key;
                cm.Username = user.Username;
                cm.Password = user.Password;
// ReSharper disable once RedundantCast - Must cast to dynamic (otherwise it throws exception)
                cm.PersistanceType = (dynamic)Enum.Parse(persistanceEnumType, "Enterprise");
                return cm.Save();
            }
            catch
            {
                return false;
            }
        }

        public static UserCredentials RestoreCredentials(string key)
        {
            try
            {
                var asm = getCredentialLibrary();
                if (asm == null)
                    return null;

                var type = asm.GetType("CredentialManagement.Credential");
                dynamic cm = Activator.CreateInstance(type);
                cm.Target = TARGET_PREFIX + key;
                if (!cm.Exists())
                    return null;
                cm.Load();
                return new UserCredentials(cm.Username, cm.Password, key);
            }
            catch
            {
                return null;
            }
           
        }


        private static Assembly getCredentialLibrary()
        {
            var loaded =
                AppDomain.CurrentDomain.GetAssemblies()
                    .FirstOrDefault(x => x.FullName.Contains(CREDENTIAL_LIBRARY_NAME));

            if (loaded == null && !_alreadyTriedLoadCredentialLibrary)
            {
                try
                {
                    Assembly.LoadFile(PATH_TO_DLL);
                }
                catch { }
                _alreadyTriedLoadCredentialLibrary = true;
                return getCredentialLibrary();
            }
            return loaded;
        }
    }
    
    class UserCredentials
    {
        public string Username { get; set; }
        public string Password { get; set; }
        public string Key { get; set; }

        public UserCredentials(string username, string password, string key)
        {
            Username = username;
            Password = password;
            Key = key;
        }
    }
}