Deobfuscation for KDE passwords

kde_deobfuscate.rb

def kde_deobfuscate(str)
  chars = str.split("")
  out = ''
  while chars.any?
    b1 = chars.shift
    if b1 == 0xef.chr
      case chars.shift
        when 0xbe.chr
          out << (0x1001F - chars.shift[0] - 0xff00).chr
        when 0xbf.chr
          out << (0x1001F - chars.shift[0] - 0xff00 - 0x40).chr
      end
    end
  end
  out
end

see http://salahuddin66.blogspot.com/2009/04/recover-kopete-password.html