Efficient byte[] to string

ToHex.cs

// Taken from https://www.bouncycastle.org/
// Adapted to create and return a string rather than write to a Stream
// https://twitter.com/mstum/status/970207754207006720

  private static readonly byte[] encodingTable =
  {
    (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7',
    (byte)'8', (byte)'9', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f'
   };

   public static string ToHexBouncyCastle(byte[] data, int off, int length)
   {
      var result = new byte[length * 2];
      var ix = 0;
      for (int i = off; i < (off + length); i++)
      {
        int v = data[i];
        result[ix++] = encodingTable[v >> 4];
        result[ix++] = encodingTable[v & 0xf];
       }

      return Encoding.ASCII.GetString(result, 0, result.Length);
    }