How to lock PDF files with password?

Situation 1:

I have some very important PDF files and I would like to add password to them to prevent other people opening them. How can I lock PDF files with high security password.

Sitiation 2:

I shared some PDF files with others, however I don't hope them print my PDF files out for their private using. So can I add password to prevent others printing PDF?

Answer:

Sometimes we may need locks for PDF and prevent them from being open randomly, especially some important and confidential files. This guide will show you how to add password to PDF files to prevent opening or printing.

1. Free download PDF Locker, then install and launch it.

2. Add PDF files to PDF Password Security. This tool supports three kinds of modes to add PDF files: add single PDF, add batch PDF files and add PDF directory.

3. Select security method.
a. choose security level (low--40-bit, Acrobat 3.0 and above; high--128-bit, Acrobat 5.0 and above)
b. permission options. If you need to restrict printing rights, you can add password to "permission password".

4. Set expiry date. This option allows you to set an expiry date, and when the limit time arrives, the password will become invalid automatically.

5. Finish the process.

Because this tool can add different passwords to many PDF files, it owns a password pool, thus you can recover your PDF password if you forgot it.

Another tips: how to extract images from PDF?