hexutils.scala

def hexify(bytes: Array[Byte]): String = {
  val builder = new StringBuilder
  for (i <- 0 until bytes.length) {
    val b = bytes(i)
    val upperNibble = (b >>> 4) & 0x0f
    val lowerNibble = b & 0x0f
    builder += Character.forDigit(upperNibble, 16)
    builder += Character.forDigit(lowerNibble, 16)
  }
  builder.result()
}

def unhexify(str: String): Array[Byte] = {
  val bytes = new Array[Byte](str.length / 2)
  for (i <- 0 until str.length / 2) {
    val upperNibble = Character.digit(str.charAt(i * 2), 16)
    val lowerNibble = Character.digit(str.charAt(i * 2 + 1), 16)
    bytes(i) = ((upperNibble << 4) | lowerNibble).toByte
  }
  bytes
}