Secure PDF
Protect a PDF with a password
Lock an unlocked PDF with AES-256 encryption and a password.
Choose a file
Choose one unlocked PDF up to 120 MB.
Protect a PDF with a password
Encrypt a PDF with AES-256, check the protected copy and save it as a separate file from the source document.
Encrypt the document with AES-256
The tool encrypts the PDF's pages, text and images with AES-256. This is different from PDF permission flags, which request restrictions such as disabled printing but may depend on the reader to enforce them.
Access still depends on the password you choose. The form requires at least six characters and a matching confirmation, but a longer unique passphrase is harder to guess than a short common word.
Choose and store the password
Encryption runs in this browser, and Rebuild does not receive or store the password. There is no recovery path through the service if the password is lost, so keep it in an appropriate password manager.
When another person needs the file, send the password through a different channel from the document. Confirm that the recipient can open the protected copy before removing an unencrypted source they still require.
Check the protected output
After encryption, the tool reopens the protected output with the supplied password and checks that every expected page is present. The download is offered only after the file can be decrypted and read.
Open the downloaded PDF in another reader and enter the password again. Check page count, visible content and any forms or links needed by the recipient before distributing the protected copy.
Protection creates a new PDF and leaves the unencrypted source unchanged. Keep that source until the recipient has confirmed access, then store or remove each copy according to the document's retention requirements and applicable local access-control rules.
Know what encryption controls
Encryption controls access to the unopened file. A person with the password may still be able to read, copy, print, capture or share its contents after opening it, depending on the PDF reader and document settings.
Password protection is not redaction: sensitive content remains inside the encrypted file. Permanently redact information that must not appear in the shared copy, check that result, then encrypt it if access also needs a password.
Questions
How is a password added to a PDF?
Choose an unlocked PDF, enter a password of at least six characters twice, then save the AES-256 encrypted copy.
Which encryption is used?
The protected PDF uses AES-256 encryption.
Where is the password stored?
The password remains in the browser page during processing and is cleared when the result is ready. Rebuild does not store it.
What if I forget the password?
The password cannot be recovered through Rebuild. Keep the source PDF and store the password in an appropriate password manager.