val length0 = source.readByte().toInt() and 0xff
    val length =
      when {
        length0 == 0b1000_0000 -> {
          throw ProtocolException("indefinite length not permitted for DER")
        }
        (length0 and 0b1000_0000) == 0b1000_0000 -> {
          // Length specified over multiple bytes.
          val lengthBytes = length0 and 0b0111_1111
          if (lengthBytes > 8) {

  }

  @Test fun `decode length overflowing Long`() {
    val buffer =
      Buffer()
        .writeByte(0b00000010)
        .writeByte(0b10001000)
        .writeByte(0b10000000)
        .writeByte(0b00000000)
        .writeByte(0b00000000)
        .writeByte(0b00000000)
        .writeByte(0b00000000)
        .writeByte(0b00000000)
        .writeByte(0b00000000)