keyIndex %= keyLength // Reassign to prevent overflow breaking counter.

          // Byte xor is experimental in Kotlin so we coerce bytes to int, xor them
          // and convert back to byte.
          val bufferInt: Int = buffer[i].toInt()
          val keyInt: Int = key[keyIndex].toInt()
          buffer[i] = (bufferInt xor keyInt).toByte()

          i++
          keyIndex++
        }
      }