Media is still accessible via it's original URL after its been sent to the recycle bin

src/Umbraco.Core/Models/Media.cs

@@ -117,6 +117,7 @@ public override void ChangeTrashedState(bool isTrashed, int parentId = -20)
             Trashed = isTrashed;
             //The Media Recycle Bin Id is -21 so we correct that here
             ParentId = parentId == -20 ? -21 : parentId;
+
         }
     }
-}
+}

src/Umbraco.Core/Services/IMediaService.cs

@@ -112,7 +112,7 @@ public interface IMediaService : IContentServiceBase
         /// <param name="mediaTypeAlias">Alias of the <see cref="IMediaType"/></param>
         /// <param name="userId">Optional id of the user creating the media item</param>
         /// <returns><see cref="IMedia"/></returns>
-        IMedia CreateMedia(string name, Guid parentId, string mediaTypeAlias, int userId = 0);
+        IMedia CreateMedia(string name, Guid parentId, string mediaTypeAlias, int userId = 0);
 
         /// <summary>
         /// Creates an <see cref="IMedia"/> object using the alias of the <see cref="IMediaType"/>

src/Umbraco.Core/Services/MediaService.cs

@@ -4,6 +4,7 @@
 using System.Globalization;
 using System.IO;
 using System.Linq;
+using System.Text.RegularExpressions;
 using System.Threading;
 using System.Xml.Linq;
 using Umbraco.Core.Configuration;
@@ -797,6 +798,7 @@ public Attempt<OperationStatus> Move(IMedia media, int parentId, int userId = 0)
                     if (media.Trashed)
                     {
                         media.ChangeTrashedState(false, parentId);
+                        UnobfuscateTrashedMedia(media);
                     }
                     Save(media, userId, false); //no events!
 
@@ -1133,6 +1135,8 @@ private Attempt<OperationStatus> MoveToRecycleBinDo(IMedia media, int userId, bo
                     //must be processed with shallowest levels first
                     var descendants = ignoreDescendants ? Enumerable.Empty<IMedia>() : GetDescendants(media).OrderBy(x => x.Level);
 
+                    ObfuscateTrashedMedia(media);
+
                     //Do the updates for this item
                     var repository = RepositoryFactory.CreateMediaRepository(uow);
                     repository.DeleteContentXml(media);
@@ -1144,8 +1148,9 @@ private Attempt<OperationStatus> MoveToRecycleBinDo(IMedia media, int userId, bo
                     {
                         repository.DeleteContentXml(descendant);
                         descendant.ChangeTrashedState(true, descendant.ParentId);
+                        ObfuscateTrashedMedia(descendant);
                         repository.AddOrUpdate(descendant);
-
+                        
                         moveInfo.Add(new MoveEventInfo<IMedia>(descendant, descendant.Path, descendant.ParentId));
                     }
 
@@ -1161,6 +1166,53 @@ private Attempt<OperationStatus> MoveToRecycleBinDo(IMedia media, int userId, bo
             }
         }
 
+        private void ObfuscateTrashedMedia(IMedia media)
+        {
+            var umbracoFile = media.GetValue<string>("umbracoFile");
+            var filename = Path.GetFileName(umbracoFile);
+            var newUmbracoFile = MediaPath(umbracoFile) + ObfuscateFilename(filename);
+            MoveFile(umbracoFile, newUmbracoFile);
+            media.SetValue("umbracoFile", newUmbracoFile);
+        }
+
+        private void UnobfuscateTrashedMedia(IMedia media)
+        {
+            var umbracoFile = media.GetValue<string>("umbracoFile");
+            var filename = Path.GetFileName(umbracoFile);
+            if (HasBeenObfuscated(filename)) 
+            {
+                var newUmbracoFile = MediaPath(umbracoFile) + UnobfuscateFilename(filename);
+                MoveFile(umbracoFile, newUmbracoFile);
+                media.SetValue("umbracoFile", newUmbracoFile);
+            }
+        }
+
+        private string MediaPath(string umbracoFile)
+        {
+            return Path.GetDirectoryName(umbracoFile).Replace("\\", "/") + "/";
+        }
+
+        private void MoveFile(string from, string to)
+        {
+            _mediaFileSystem.CopyFile(from, to);
+            _mediaFileSystem.DeleteFile(from);
+        }
+
+        private string ObfuscateFilename(string filename)
+        {
+            return Guid.NewGuid() + "$" + filename;
+        }
+
+        private string UnobfuscateFilename(string filename)
+        {
+            return filename.Split(new[] {'$'}, 2)[1];
+        }
+
+        private bool HasBeenObfuscated(string filename)
+        {
+            return Regex.IsMatch(filename, @"^[{(]?[0-9A-F]{8}[-]?(?:[0-9A-F]{4}[-]?){3}[0-9A-F]{12}[)}]?\\$");
+        }
+
 
         /// <summary>
         /// Permanently deletes an <see cref="IMedia"/> object as well as all of its Children.
@@ -1381,6 +1433,14 @@ private IEnumerable<IMedia> UpdatePropertiesOnChildren(IEnumerable<IMedia> child
                 if (parentTrashed != child.Trashed)
                 {
                     child.ChangeTrashedState(parentTrashed, child.ParentId);
+                    if (parentTrashed)
+                    {
+                        ObfuscateTrashedMedia(child);
+                    }
+                    else
+                    {
+                        UnobfuscateTrashedMedia(child);
+                    }
                 }
 
                 eventInfo.Add(new MoveEventInfo<IMedia>(child, originalPath, child.ParentId));