Base64.kt for Kotlin

Base64.kt

fun String.encodeBase64ToString(): String = String(this.toByteArray().encodeBase64())
fun String.encodeBase64ToByteArray(): ByteArray = this.toByteArray().encodeBase64()
fun ByteArray.encodeBase64ToString(): String = String(this.encodeBase64())

fun String.decodeBase64(): String = String(this.toByteArray().decodeBase64())
fun String.decodeBase64ToByteArray(): ByteArray = this.toByteArray().decodeBase64()
fun ByteArray.decodeBase64ToString(): String = String(this.decodeBase64())

fun ByteArray.encodeBase64(): ByteArray {
  val table = (CharRange('A', 'Z') + CharRange('a', 'z') + CharRange('0', '9') + '+' + '/').toCharArray()
  val output = ByteArrayOutputStream()
  var padding = 0
  var position = 0
  while (position < this.size) {
    var b = this[position].toInt() and 0xFF shl 16 and 0xFFFFFF
    if (position + 1 < this.size) b = b or (this[position + 1].toInt() and 0xFF shl 8) else padding++
    if (position + 2 < this.size) b = b or (this[position + 2].toInt() and 0xFF) else padding++
    for (i in 0 until 4 - padding) {
      val c = b and 0xFC0000 shr 18
      output.write(table[c].toInt())
      b = b shl 6
    }
    position += 3
  }
  for (i in 0 until padding) {
    output.write('='.toInt())
  }
  return output.toByteArray()
}

fun ByteArray.decodeBase64(): ByteArray {
  val table = intArrayOf(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1,
      -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
      -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1)

  val output = ByteArrayOutputStream()
  var position = 0
  while (position < this.size) {
    var b: Int
    if (table[this[position].toInt()] != -1) {
      b = table[this[position].toInt()] and 0xFF shl 18
    } else {
      position++
      continue
    }
    var count = 0
    if (position + 1 < this.size && table[this[position + 1].toInt()] != -1) {
      b = b or (table[this[position + 1].toInt()] and 0xFF shl 12)
      count++
    }
    if (position + 2 < this.size && table[this[position + 2].toInt()] != -1) {
      b = b or (table[this[position + 2].toInt()] and 0xFF shl 6)
      count++
    }
    if (position + 3 < this.size && table[this[position + 3].toInt()] != -1) {
      b = b or (table[this[position + 3].toInt()] and 0xFF)
      count++
    }
    while (count > 0) {
      val c = b and 0xFF0000 shr 16
      output.write(c.toChar().toInt())
      b = b shl 8
      count--
    }
    position += 4
  }
  return output.toByteArray()
}

What you think about publish it like library?

@jershell not sure how well it will have aged but feel free to do so 💪

Took your solution, thanks!