Protect PDF

Protect PDF asks for a password and an optional owner password. The measured save did not lock the file. A reader opened it with no password.

The saved file still opens

split-six.pdf is 1,910 bytes and six pages. The password cover-42 was sent as both the user password and the owner password. The worker saved protected-out.pdf at 1,915 bytes in 64 ms. Loading that file without a password succeeded. The page count stayed 6. Nothing in the download asked for cover-42. The button label is Run Protect PDF. The download control says Download file. Keep the original. This output is not a locked copy of it. Each source page was 612 by 792 points. Those sizes were still there after the save.

An empty password never uploads

Leave the password blank and the form shows Please enter a password to protect the PDF. The file stays on your computer. If a blank password reaches the server, the reply is Password is required. The owner field can stay empty. Filling it did not change the measured result: the file still opened. Both fields are password boxes on the form. /tool/unlock-pdf asks for a password on a file that is already locked, and that page also failed to open the test file.

What to use when you need a real lock

This page cannot be the lock step before you email a contract. Use a desktop app that writes a password you can test by closing the file and opening it again. /tool/merge-pdf, /tool/split-pdf, and /tool/rotate-pdf change pages and do not add a password either. The upload cap here is 25 MB and one PDF. Temporary files are removed after the job. That cleanup is not the same as encryption. The measured download grew by 5 bytes, from 1,910 to 1,915, and still opened on the first try.