using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read))
            using (BinaryReader br = new BinaryReader(fs))
            {
                newFile = br.ReadBytes((int)fs.Length);
                crc = CRC32Bytes(newFile);
                fileSizeUncompressed = (UInt32)newFile.Length;
            }

to

            newFile = File.ReadAllBytes(filename);
            crc = CRC32Bytes(newFile);
            fileSizeUncompressed = (UInt32)newFile.Length;