C#のstringとbyteの相互変換

shift-jisは可変長だから、自分で勝手に2バイト区切りにしては駄目

            {
                string sOriginal = "ユニＣｏｄｅのbyte変換";
                byte[] arrBytes = Encoding.Unicode.GetBytes(sOriginal);
                //foreach (byte b in bytesData) Debug.WriteLine(b);
                Debug.WriteLine(BitConverter.ToString(arrBytes));
                string hexString = BitConverter.ToString(arrBytes).Replace("-", "");
                Debug.WriteLine(hexString);

                byte[] repack = new byte[hexString.Length / 2];
                for (var i = 0; i < hexString.Length / 2; i++)
                {
                    var hexChar = hexString.Substring(2 * i, 2);
                    repack[i] = Convert.ToByte(hexChar, 16);
                }
                Debug.WriteLine(Encoding.Unicode.GetString(repack));

                //2バイトずつもどす
                byte[] tmp = new byte[2];
                for (int i = 0; i < arrBytes.Length / 2; i++)
                {
                    tmp[0] = arrBytes[2 * i + 0];
                    tmp[1] = arrBytes[2 * i + 1];
                    Debug.WriteLine(Encoding.Unicode.GetString(tmp));
                }
            }
            Debug.WriteLine("---");
            {
                string sOriginal = "シフトjisのbyte変換";
                byte[] arrBytes = Encoding.GetEncoding("Shift_JIS").GetBytes(sOriginal);
                //foreach (byte b in bytesData) Debug.WriteLine(b);
                Debug.WriteLine(BitConverter.ToString(arrBytes));
                string hexString = BitConverter.ToString(arrBytes).Replace("-", "");
                Debug.WriteLine(hexString);

                byte[] repack = new byte[hexString.Length / 2];
                for (var i = 0; i < hexString.Length / 2; i++)
                {
                    var hexChar = hexString.Substring(2 * i, 2);
                    repack[i] = Convert.ToByte(hexChar, 16);
                }
                Debug.WriteLine(Encoding.GetEncoding("Shift_JIS").GetString(repack));

                //shiftjisは可変長なので、2バイトで区切るとくしゃくしゃになる
                byte[] tmp = new byte[2];
                for (int i = 0; i < arrBytes.Length / 2; i++)
                {
                    tmp[0] = arrBytes[2 * i + 0];
                    tmp[1] = arrBytes[2 * i + 1];
                    Debug.WriteLine(Encoding.GetEncoding("Shift_JIS").GetString(tmp));
                }
            }

実行結果

E6-30-CB-30-23-FF-4F-FF-44-FF-45-FF-6E-30-62-00-79-00-74-00-65-00-09-59-DB-63
E630CB3023FF4FFF44FF45FF6E3062007900740065000959DB63
ユニＣｏｄｅのbyte変換
ユ
ニ
Ｃ
ｏ
ｄ
ｅ
の
b
y
t
e
変
換
---
83-56-83-74-83-67-6A-69-73-82-CC-62-79-74-65-95-CF-8A-B7
8356837483676A697382CC6279746595CF8AB7
シフトjisのbyte変換
シ
フ
ト
ji
s・
ﾌb
yt
e・
ﾏ・