Create a hash for all files in a directory, including file content, name, and path.

GetDirectoryHash.cs

public static byte[] GetDirectoryHash(string path)
        {
            var fileCount = 0;
            var fileHasher = SHA1Managed.Create();
            var sumHasher = SHA1Managed.Create();
            sumHasher.Initialize();
            var sw = new Stopwatch();
            sw.Start();

            foreach (var file in Directory.EnumerateFiles(path, "*.*", SearchOption.AllDirectories))
            {
                using (var str = File.OpenRead(file))
                {
                    var hash = fileHasher.ComputeHash(str);
                    sumHasher.TransformBlock(hash, 0, hash.Length, null, 0);
                    //hash the name and path of the file...
                    var filePath = Encoding.UTF8.GetBytes(file);
                    sumHasher.TransformBlock(filePath, 0, filePath.Length, null, 0);
                    fileCount++;
                }
            }
            sumHasher.TransformFinalBlock(new byte[0], 0, 0);
            sw.Stop();
            Console.WriteLine("Hashed {0} files in {1} milliseconds.", fileCount, sw.ElapsedMilliseconds);
            return sumHasher.Hash;
        }