diff --git a/AaxDecrypter/AaxcDownloadConverter.cs b/AaxDecrypter/AaxcDownloadConverter.cs
index 2944c9d7..87629279 100644
--- a/AaxDecrypter/AaxcDownloadConverter.cs
+++ b/AaxDecrypter/AaxcDownloadConverter.cs
@@ -128,12 +128,32 @@ namespace AaxDecrypter
         public bool Step2_GetMetadata()
         {
             //Get metadata from the file over http
-            var client = new System.Net.Http.HttpClient();
-            client.DefaultRequestHeaders.Add("User-Agent", downloadLicense.UserAgent);
-            var networkFile = NetworkFileAbstraction.CreateAsync(client, new Uri(downloadLicense.DownloadUrl)).GetAwaiter().GetResult();
+
+            NetworkFileStreamPersister nfsPersister;
+
+            string jsonDownloadState = PathLib.ReplaceExtension(outputFileName, ".json");
+            string tempFile = PathLib.ReplaceExtension(outputFileName, ".aaxc");
+
+            if (File.Exists(jsonDownloadState))
+            {
+                nfsPersister = new NetworkFileStreamPersister(jsonDownloadState);
+            }
+            else
+            {
+                var headers = new System.Net.WebHeaderCollection();
+                headers.Add("User-Agent", downloadLicense.UserAgent);
+
+                NetworkFileStream networkFileStream = new NetworkFileStream(tempFile, new Uri(downloadLicense.DownloadUrl), 0, headers);
+                nfsPersister = new NetworkFileStreamPersister(networkFileStream, jsonDownloadState);
+                nfsPersister.Target.BeginDownloading().GetAwaiter().GetResult();
+            }
+
+            var networkFile = new NetworkFileAbstraction(nfsPersister.Target);
+
+            nfsPersister.Dispose();
 
             aaxcTagLib = new AaxcTagLibFile(networkFile);
-
+            
             if (coverArt is null && aaxcTagLib.AppleTags.Pictures.Length > 0)
             {
                 coverArt = aaxcTagLib.AppleTags.Pictures[0].Data.Data;
diff --git a/AaxDecrypter/NetworkFileAbstraction.cs b/AaxDecrypter/NetworkFileAbstraction.cs
index 136236ca..60f52a9f 100644
--- a/AaxDecrypter/NetworkFileAbstraction.cs
+++ b/AaxDecrypter/NetworkFileAbstraction.cs
@@ -12,26 +12,10 @@ namespace AaxDecrypter
     {
         private NetworkFileStream aaxNetworkStream;
 
-        public static async Task<NetworkFileAbstraction> CreateAsync(HttpClient client, Uri webFileUri)
+        public NetworkFileAbstraction( NetworkFileStream networkFileStream)
         {
-            var response = await client.GetAsync(webFileUri, HttpCompletionOption.ResponseHeadersRead);
-
-            if (response.StatusCode != System.Net.HttpStatusCode.OK)
-                throw new Exception("Can't read file from client.");
-
-            var contentLength = response.Content.Headers.ContentLength ?? 0;
-
-            var networkStream = await response.Content.ReadAsStreamAsync();
-
-            var networkFile = new NetworkFileAbstraction(Path.GetFileName(webFileUri.LocalPath), networkStream, contentLength);
-
-            return networkFile;
-        }
-
-        private NetworkFileAbstraction(string fileName, Stream netStream, long contentLength)
-        {
-            Name = fileName;
-            aaxNetworkStream = new NetworkFileStream(netStream, contentLength);
+            Name = networkFileStream.SaveFilePath;
+            aaxNetworkStream = networkFileStream;
         }
         public string Name { get; private set; }
 
@@ -43,93 +27,5 @@ namespace AaxDecrypter
         {
             aaxNetworkStream.Close();
         }
-
-        private class NetworkFileStream : Stream
-        {
-            private const int BUFF_SZ = 2 * 1024;
-
-            private FileStream _fileBacker;
-
-            private Stream _networkStream;
-
-            private long networkBytesRead = 0;
-
-            private long _contentLength;
-            public NetworkFileStream(Stream netStream, long contentLength)
-            {
-                _networkStream = netStream;
-                _contentLength = contentLength;
-                _fileBacker = File.Create(Path.GetTempFileName(), BUFF_SZ, FileOptions.DeleteOnClose);
-            }
-            public override bool CanRead => true;
-
-            public override bool CanSeek => true;
-
-            public override bool CanWrite => false;
-
-            public override long Length => _contentLength;
-
-            public override long Position { get => _fileBacker.Position; set => Seek(value, 0); }
-
-            public override void Flush()
-            {
-                throw new NotImplementedException();
-            }
-            public override void SetLength(long value)
-            {
-                throw new NotImplementedException();
-            }
-            public override void Write(byte[] buffer, int offset, int count)
-            {
-                throw new NotImplementedException();
-            }
-            public override int Read(byte[] buffer, int offset, int count)
-            {
-                long requiredLength = Position + count;
-
-                if (requiredLength > networkBytesRead)
-                    readWebFileToPosition(requiredLength);
-
-                return _fileBacker.Read(buffer, offset, count);
-            }
-
-            public override long Seek(long offset, SeekOrigin origin)
-            {
-                long newPosition = (long)origin + offset;
-
-                if (newPosition > networkBytesRead)
-                    readWebFileToPosition(newPosition);
-
-                _fileBacker.Position = newPosition;
-                return newPosition;
-            }
-
-            public override void Close()
-            {
-                _fileBacker.Close();
-                _networkStream.Close();
-            }
-            /// <summary>
-            /// Read more data from <see cref="_networkStream"/> into <see cref="_fileBacker"/> as needed. 
-            /// </summary>
-            /// <param name="requiredLength">Length of strem required for the operation.</param>
-            private void readWebFileToPosition(long requiredLength)
-            {
-                byte[] buff = new byte[BUFF_SZ];
-
-                long backerPosition = _fileBacker.Position;
-
-                _fileBacker.Position = networkBytesRead;
-
-                while (networkBytesRead < requiredLength)
-                {
-                    int bytesRead = _networkStream.Read(buff, 0, BUFF_SZ);
-                    _fileBacker.Write(buff, 0, bytesRead);
-                    networkBytesRead += bytesRead;
-                }
-
-                _fileBacker.Position = backerPosition;
-            }
-        }
     }
 }
diff --git a/AaxDecrypter/NetworkFileStream.cs b/AaxDecrypter/NetworkFileStream.cs
new file mode 100644
index 00000000..bb25300b
--- /dev/null
+++ b/AaxDecrypter/NetworkFileStream.cs
@@ -0,0 +1,431 @@
+using Dinah.Core;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using System;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace AaxDecrypter
+{
+    /// <summary>
+    /// A <see cref="CookieContainer"/> for a single Uri.
+    /// </summary>
+    public class SingleUriCookieContainer : CookieContainer
+    {
+        public SingleUriCookieContainer(Uri uri)
+        {
+            Uri = uri;
+        }
+        public Uri Uri { get; }
+
+        public CookieCollection GetCookies() => base.GetCookies(Uri);
+    }
+
+    /// <summary>
+    /// A resumable, simultaneous file downloader and reader.
+    /// </summary>
+    public class NetworkFileStream : Stream, IUpdatable
+    {
+        public event EventHandler Updated;
+
+        #region Public Properties
+
+        /// <summary>
+        /// Location to save the downloaded data.
+        /// </summary>
+        [JsonProperty(Required = Required.Always)]
+        public string SaveFilePath { get; }
+
+        /// <summary>
+        /// Http(s) address of the file to download.
+        /// </summary>
+        [JsonProperty(Required = Required.Always)]
+        public Uri Uri { get; }
+
+        /// <summary>
+        /// All cookies set by caller or by the remote server.
+        /// </summary>
+        [JsonProperty(Required = Required.Always)]
+        public SingleUriCookieContainer CookieContainer { get; }
+
+        /// <summary>
+        /// Http headers to be sent to the server with the request.
+        /// </summary>
+        [JsonProperty(Required = Required.Always)]
+        public WebHeaderCollection RequestHeaders { get; private set; }
+
+        /// <summary>
+        /// The position in <see cref="SaveFilePath"/> that has been written and flushed to disk.
+        /// </summary>
+        [JsonProperty(Required = Required.Always)]
+        public long WritePosition { get; private set; }
+
+        /// <summary>
+        /// The total length of the <see cref="Uri"/> file to download.
+        /// </summary>
+        [JsonProperty(Required = Required.Always)]
+        public long ContentLength { get; private set; }
+
+        #endregion
+
+        #region Private Properties
+
+        private HttpWebRequest HttpRequest { get; }
+        private FileStream _writeFile { get; }
+        private FileStream _readFile { get; }
+        private Stream _networkStream { get; set; }
+        private bool hasBegunDownloading { get; set; }
+        private bool isCancelled { get; set; }
+        private Action cancelDownloadCallback { get; set; }
+
+        #endregion
+
+        #region Constants
+
+        //Download buffer size
+        private const int DOWNLOAD_BUFF_SZ = 4 * 1024;
+
+        //NetworkFileStream will flush all data in _writeFile to disk after every
+        //DATA_FLUSH_SZ bytes are written to the file stream.
+        private const int DATA_FLUSH_SZ = 1024 * 1024;
+
+        #endregion
+
+        #region Constructor
+
+        /// <summary>
+        /// A resumable, simultaneous file downloader and reader.
+        /// </summary>
+        /// <param name="saveFilePath">Path to a location on disk to save the downloaded data from <paramref name="uri"/></param>
+        /// <param name="uri">Http(s) address of the file to download.</param>
+        /// <param name="writePosition">The position in <paramref name="uri"/> to begin downloading.</param>
+        /// <param name="requestHeaders">Http headers to be sent to the server with the <see cref="HttpWebRequest"/>.</param>
+        /// <param name="cookies">A <see cref="SingleUriCookieContainer"/> with cookies to send with the <see cref="HttpWebRequest"/>. It will also be populated with any cookies set by the server. </param>
+        public NetworkFileStream(string saveFilePath, Uri uri, long writePosition = 0, WebHeaderCollection requestHeaders = null, SingleUriCookieContainer cookies = null)
+        {
+            ArgumentValidator.EnsureNotNullOrWhiteSpace(saveFilePath, nameof(saveFilePath));
+            ArgumentValidator.EnsureNotNullOrWhiteSpace(uri?.AbsoluteUri, nameof(uri));
+            ArgumentValidator.EnsureGreaterThan(writePosition, nameof(writePosition), -1);
+
+            if (!Directory.Exists(Path.GetDirectoryName(saveFilePath)))
+                throw new ArgumentException($"Specified {nameof(saveFilePath)} directory \"{Path.GetDirectoryName(saveFilePath)}\" does not exist.");
+
+            SaveFilePath = saveFilePath;
+            Uri = uri;
+            WritePosition = writePosition;
+            RequestHeaders = requestHeaders ?? new WebHeaderCollection();
+            CookieContainer = cookies ?? new SingleUriCookieContainer(uri);
+
+            HttpRequest = WebRequest.CreateHttp(uri);
+
+            HttpRequest.CookieContainer = CookieContainer;
+            HttpRequest.Headers = RequestHeaders;
+            //If NetworkFileStream is resuming, Header will already contain a range.
+            HttpRequest.Headers.Remove("Range");
+            HttpRequest.AddRange(WritePosition);
+
+            _writeFile = new FileStream(SaveFilePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.ReadWrite)
+            {
+                Position = WritePosition
+            };
+
+            _readFile = new FileStream(SaveFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
+        }
+
+        #endregion
+
+        #region Downloader
+
+        /// <summary>
+        /// Update the <see cref="JsonFilePersister"/>.
+        /// </summary>
+        private void Update()
+        {
+            RequestHeaders = HttpRequest.Headers;
+            Updated?.Invoke(this, new EventArgs());
+        }
+
+        /// <summary>
+        /// Begins downloading <see cref="Uri"/> to <see cref="SaveFilePath"/> in a background thread.
+        /// </summary>
+        public async Task BeginDownloading()
+        {
+            if (ContentLength != 0 && WritePosition == ContentLength)
+                return;
+
+            if (ContentLength != 0 && WritePosition > ContentLength)
+                throw new Exception($"Specified write position (0x{WritePosition:X10}) is larger than the file size.");
+
+            var response = await HttpRequest.GetResponseAsync() as HttpWebResponse;
+
+            if (response.StatusCode != HttpStatusCode.PartialContent)
+                throw new Exception($"Server at {Uri.Host} responded with unexpected status code: {response.StatusCode}.");
+
+            if (response.Headers.GetValues("Accept-Ranges").FirstOrDefault(r => r.EqualsInsensitive("bytes")) is null)
+                throw new Exception($"Server at {Uri.Host} does not support Http ranges");
+
+            //Content length is the length of the range request, and it is only equal
+            //to the complete file length if requesting Range: bytes=0-
+            if (WritePosition == 0)
+                ContentLength = response.ContentLength;
+
+            _networkStream = response.GetResponseStream();
+
+            //Download the file in the background.
+            Thread downloadThread = new Thread(() => DownloadFile());
+            downloadThread.Start();
+
+            while(!File.Exists(SaveFilePath) && new FileInfo(SaveFilePath).Length > 1000)
+            {
+                Thread.Sleep(100);
+            }
+
+            hasBegunDownloading = true;
+            return;
+        }
+
+        /// <summary>
+        /// Downlod <see cref="Uri"/> to <see cref="SaveFilePath"/>.
+        /// </summary>
+        private void DownloadFile()
+        {
+            long downloadPosition = WritePosition;
+            long nextFlush = downloadPosition + DATA_FLUSH_SZ;
+
+            byte[] buff = new byte[DOWNLOAD_BUFF_SZ];
+            do
+            {
+                int bytesRead = _networkStream.Read(buff, 0, DOWNLOAD_BUFF_SZ);
+                _writeFile.Write(buff, 0, bytesRead);
+
+                downloadPosition += bytesRead;
+
+                if (downloadPosition > nextFlush)
+                {
+                    _writeFile.Flush();
+                    WritePosition = downloadPosition;
+                    Update();
+
+                    nextFlush = downloadPosition + DATA_FLUSH_SZ;
+                }
+
+            } while (downloadPosition < ContentLength && !isCancelled);
+
+            _writeFile.Close();
+            WritePosition = downloadPosition;
+            Update();
+            _networkStream.Close();
+
+            if (!isCancelled && WritePosition < ContentLength)
+                throw new Exception("File download ended before finishing.");
+
+            if (WritePosition > ContentLength)
+                throw new Exception("Downloaded file is larger than expected.");
+
+            cancelDownloadCallback?.Invoke();
+        }
+
+        #endregion
+
+        #region Json Connverters
+
+        public static JsonSerializerSettings GetJsonSerializerSettings()
+        {
+            var settings = new JsonSerializerSettings();
+            settings.Converters.Add(new CookieContainerConverter());
+            settings.Converters.Add(new WebHeaderCollectionConverter());
+            return settings;
+        }
+
+        internal class CookieContainerConverter : JsonConverter
+        {
+            public override bool CanConvert(Type objectType)
+                => objectType == typeof(SingleUriCookieContainer);
+
+            public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+            {
+                var jObj = JObject.Load(reader);
+
+                var result = new SingleUriCookieContainer(new Uri(jObj["Uri"].Value<string>()))
+                {
+                    Capacity = jObj["Capacity"].Value<int>(),
+                    MaxCookieSize = jObj["MaxCookieSize"].Value<int>(),
+                    PerDomainCapacity = jObj["PerDomainCapacity"].Value<int>()
+                };
+
+                var cookieList = jObj["Cookies"].ToList();
+
+                foreach (var cookie in cookieList)
+                {
+                    result.Add(
+                        new Cookie
+                        {
+                            Comment = cookie["Comment"].Value<string>(),
+                            HttpOnly = cookie["HttpOnly"].Value<bool>(),
+                            Discard = cookie["Discard"].Value<bool>(),
+                            Domain = cookie["Domain"].Value<string>(),
+                            Expired = cookie["Expired"].Value<bool>(),
+                            Expires = cookie["Expires"].Value<DateTime>(),
+                            Name = cookie["Name"].Value<string>(),
+                            Path = cookie["Path"].Value<string>(),
+                            Port = cookie["Port"].Value<string>(),
+                            Secure = cookie["Secure"].Value<bool>(),
+                            Value = cookie["Value"].Value<string>(),
+                            Version = cookie["Version"].Value<int>(),
+                        });
+                }
+
+                return result;
+            }
+
+            public override bool CanWrite => true;
+
+            public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+            {
+                var cookies = value as SingleUriCookieContainer;
+                var obj = (JObject)JToken.FromObject(value);
+                var container = cookies.GetCookies();
+                var propertyNames = container.Select(c => JToken.FromObject(c));
+                obj.AddFirst(new JProperty("Cookies", new JArray(propertyNames)));
+                obj.WriteTo(writer);
+            }
+        }
+
+        internal class WebHeaderCollectionConverter : JsonConverter
+        {
+            public override bool CanConvert(Type objectType)
+                => objectType == typeof(WebHeaderCollection);
+
+            public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+            {
+                var jObj = JObject.Load(reader);
+                var result = new WebHeaderCollection();
+
+                foreach (var kvp in jObj)
+                {
+                    result.Add(kvp.Key, kvp.Value.Value<string>());
+                }
+
+                return result;
+            }
+
+            public override bool CanWrite => true;
+
+            public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+            {
+                JObject jObj = new JObject();
+                Type type = value.GetType();
+                var headers = value as WebHeaderCollection;
+                var jHeaders = headers.AllKeys.Select(k => new JProperty(k, headers[k]));
+                jObj.Add(jHeaders);
+                jObj.WriteTo(writer);
+            }
+        }
+
+        #endregion
+
+        #region Download Stream Reader
+
+        [JsonIgnore]
+        public override bool CanRead => true;
+
+        [JsonIgnore]
+        public override bool CanSeek => true;
+
+        [JsonIgnore]
+        public override bool CanWrite => false;
+
+        [JsonIgnore]
+        public override long Length => ContentLength;
+
+        [JsonIgnore]
+        public override long Position { get => _readFile.Position; set => Seek(value, SeekOrigin.Begin); }
+
+        [JsonIgnore]
+        public override bool CanTimeout => base.CanTimeout;
+
+        [JsonIgnore]
+        public override int ReadTimeout { get => base.ReadTimeout; set => base.ReadTimeout = value; }
+
+        [JsonIgnore]
+        public override int WriteTimeout { get => base.WriteTimeout; set => base.WriteTimeout = value; }
+
+        public override void Flush() => throw new NotImplementedException();
+        public override void SetLength(long value) => throw new NotImplementedException();
+        public override void Write(byte[] buffer, int offset, int count) => throw new NotImplementedException();
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            if (!hasBegunDownloading)
+                throw new Exception($"Must call {nameof(BeginDownloading)} before attempting to read {nameof(NetworkFileStream)};");
+
+            //read operation will block until file contains enough data
+            //to fulfil the request.
+            return _readFile.Read(buffer, offset, count);
+        }
+
+        public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            if (!hasBegunDownloading)
+                throw new Exception($"Must call {nameof(BeginDownloading)} before attempting to read {nameof(NetworkFileStream)};");
+
+            //read operation will block until file contains enough data
+            //to fulfil the request.
+            return await _readFile.ReadAsync(buffer, offset, count, cancellationToken);
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            long newPosition;
+
+            switch (origin)
+            {
+                case SeekOrigin.Current:
+                    newPosition = Position + offset;
+                    break;
+                case SeekOrigin.End:
+                    newPosition = ContentLength + offset;
+                    break;
+                default:
+                    newPosition = offset;
+                    break;
+            }
+
+            ReadToPosition(newPosition);
+
+            _readFile.Position = newPosition;
+            return newPosition;
+        }
+
+        /// <summary>
+        /// Ensures that the file has downloaded to at least <paramref name="neededPosition"/>, then returns.
+        /// </summary>
+        /// <param name="neededPosition">The minimum required data length in <see cref="SaveFilePath"/>.</param>
+        private void ReadToPosition(long neededPosition)
+        {
+            long totalBytesRead = _readFile.Position;
+
+            byte[] buff = new byte[DOWNLOAD_BUFF_SZ];
+            do
+            {
+                totalBytesRead += Read(buff, 0, DOWNLOAD_BUFF_SZ);
+            } while (totalBytesRead < neededPosition);
+        }
+        public override void Close()
+        {
+            isCancelled = true;
+            cancelDownloadCallback = () =>
+            {
+                _readFile.Close();
+                _writeFile.Close();
+                _networkStream?.Close();
+                Update();
+            };
+        }
+
+        #endregion
+    }
+}
diff --git a/AaxDecrypter/NetworkFileStreamPersister.cs b/AaxDecrypter/NetworkFileStreamPersister.cs
new file mode 100644
index 00000000..fc79a5c6
--- /dev/null
+++ b/AaxDecrypter/NetworkFileStreamPersister.cs
@@ -0,0 +1,23 @@
+using Dinah.Core.IO;
+using Newtonsoft.Json;
+
+namespace AaxDecrypter
+{
+    internal class NetworkFileStreamPersister : JsonFilePersister<NetworkFileStream>
+    {
+
+		/// <summary>Alias for Target </summary>
+		public NetworkFileStream Identity => Target;
+
+		/// <summary>uses path. create file if doesn't yet exist</summary>
+		public NetworkFileStreamPersister(NetworkFileStream networkFileStream, string path, string jsonPath = null)
+			: base(networkFileStream, path, jsonPath) { }
+
+		/// <summary>load from existing file</summary>
+		public NetworkFileStreamPersister(string path, string jsonPath = null)
+			: base(path, jsonPath) { }
+
+		protected override JsonSerializerSettings GetSerializerSettings() => NetworkFileStream.GetJsonSerializerSettings();
+
+    }
+}