I want to make some PDFs (I can use doPDF for that) but I also want to lock the copy/paste function on these files and want to have an almost uncrackable password on the file itself. How can I do that ?
If you want the content to be readable by anyone but not copyable - can't be done. You can make it harder with passwording and putting a watermark on each page, try to make it unprintable but anyone can capture a page image, screen-grab or even take a photo of the screen, and reproduce it or feed it into OCR software.
As regards copyright theft: ensure there is a copyright statement then if you find anyone has copied chunks of your work you can (in theory) take action against them.
Primo PDF will let you password a .pdf file and the best thing is that it is freeware:
How to password a pdf file using primo PDF:
Hello, A 14-15 character long password with the combination of letters,numbers and at least one special character
creates a strong password which is impossibe to crack with brute forcing.
do not use dictinary words.
This will save the password from brute force attack ,which cracks the password by guessing combination, and they use dictionary words for that.
PDF Protect can do this. Adobe Acrobat also has a similar feature.