PDF のパスワードを解除。(注意：印刷「許可しない」フラグなどが外れてしまいます)

FreePdf.scala

import java.io.FileOutputStream
import com.itextpdf.text.DocWriter
import com.itextpdf.text.pdf.{PdfStamper, PdfReader}

object FreePdf {
  val usage = """
    |FreePdf [-password password] input-pdf-file output-pdf-file
    |  Option:
    |    -password password: Owner(Master) password of the file
  """.stripMargin

  def getOptions(opts: Map[String, String], xs: List[String]) : Map[String, String] = xs match {
    case "-password" :: password :: tail => getOptions(opts + ("password" -> password), tail)
    case Nil => throw new Exception("infile/outfile not specified")
    case infile :: Nil => throw new Exception("outfile not specified")
    case infile :: outfile :: Nil => opts + ("infile" -> infile) + ("outfile" -> outfile)
    case infile :: outfile :: extra => throw new Exception("unknown command line argument:" + extra.mkString(" "))
  }

  def main(args: Array[String]) {
    val opts: Map[String, String] =
      try {
        getOptions(Map(), args.toList)
      } catch {
        case e: Exception => {
          println(usage)
          println(e.getMessage)
          exit(-1)
        }
      }

    val password = opts.getOrElse("password", "")
    val encryptedFileName = opts("infile")
    val decryptedFileName = opts("outfile")

    val reader = new PdfReader(encryptedFileName, DocWriter.getISOBytes(password));
    val stamper = new PdfStamper(reader, new FileOutputStream(decryptedFileName));
    stamper.close
  }
}