AES-256 PDF protection
Protect access first; do not confuse a password with complete control
This tool creates an AES-256 password-protected PDF in your browser. The password is required to open the document. The output also requests restrictions on copying and modification, while printing remains allowed.
Threat model: this helps protect a file from someone who does not know the open password.
It does not make visible information impossible to photograph, retype or capture after an authorized viewer opens the document.
What the current protection settings actually do
| Action | Current output |
|---|---|
| Open PDF without password | Blocked |
| Encryption | AES-256 |
| Printing | Allowed |
| Copying | Requested as disallowed |
| Modification | Requested as disallowed |
Permission restrictions can depend on the PDF reader. Treat them as usage controls, not as an absolute guarantee against an authorized viewer.
Password handling matters
- Use a unique password or passphrase; longer is better.
- Do not reuse an account password.
- For sensitive documents, send the file and password through separate channels.
- Keep an authorized unprotected master if you may need to edit the document later.
Protection is not redaction
If a recipient is allowed to open the PDF but must not see a particular name, account number or address, password protection does not solve that problem. Remove or properly redact the information before sharing.
Test the actual downloaded file
- Protect a copy, not your only source.
- Close the browser preview and open the downloaded PDF in a normal reader.
- Confirm the password prompt appears.
- Test the correct password and one incorrect password.
- Check any document features that matter after encryption.
Signed PDFs need special care
Encrypting or otherwise modifying a certificate-signed PDF changes document bytes and can affect signature validation. Preserve the signed original and follow the workflow required by the signer or receiving organization.
File handling
The PDF and password are processed in your browser by the encryption library. PDFNexa does not receive the selected document or the password. External script files are downloaded to run the tool, but the PDF bytes remain in the local browser workflow.