When you protect a PDF, GekiPDF applies AES-256 encryption using your user password. The file itself stores the encrypted data plus a small header that says 'this file is locked'. Without the exact password, the decryption key never forms, so the content stays unreadable - even for us or any other software.
A forgotten password means no recovery path. AES-256 has 2^256 possible keys, and trying them all would take longer than the age of the universe. Your only option is to remember it or use an unprotected copy if you saved one earlier. GekiPDF's protect-pdf tool adds this lock in seconds, but it cannot reverse it.
Frequently asked questions
Can GekiPDF unlock my own protected file if I forget the password?
No. The file uses AES-256 encryption with your user password. Without that exact string, decryption is mathematically impossible. You can only re-protect a new copy from the original source.
What happens to my file after I protect it on GekiPDF?
The uploaded file is processed and then deleted after one hour. No copy remains on our servers, and we do not store passwords or keys. You keep only the downloaded encrypted version.
Is there a size limit for protecting a PDF?
Yes, files up to 50 MB are accepted. Larger files need to be split first using our split-pdf tool, then each part can be protected separately.
Do it in the full tool
Open Protect PDF for all options, or jump straight to another step below.