How to crack protected PDF

If you have copy-paste protected pdf, but you need to copy text, how to remove this kind of security. You need Linux only… and make two commands.
First, convert secured pdf to postscript file.

~$ pdftops secured_file.pdf

next, convert to pdf back

~$ ps2pdf converted.pdf

after done, you should have unsecured PDF file. Now you can copy and paste to 🙂