Encrypt PDF
1選擇 PDF 檔案
拖曳 PDF 到此處，或點擊選擇
僅支援 .pdf 格式，最大 100MB
Protect a PDF with an open password and optional permission limits before sharing contracts, resumes, ID scans, and other sensitive files.
Related
What is PDF encryption?
PDF encryption adds password protection to a PDF so anyone who receives the file must pass a check before reading it. This tool always sets an open password and can also limit printing, copying, editing, commenting, form filling, and page assembly.
The open password answers “who can see the file,” while permission settings answer “what they can do after opening it.” If you send contracts, quotes, ID scans, or internal reports outside your team, you will usually want both layers.
The current tool uses AES-128 by default, which works well with most modern PDF readers. If the recipient still relies on an older reader, you can switch to compatibility mode, but that lowers the security level.
Permission flags in PDFs still depend on whether the reader follows the standard. They raise the barrier for copying, printing, and editing, but they do not replace enterprise DRM, digital signatures, or stricter document controls.
Use Cases
- Add an open password before sending contracts, quotes, or proposals to clients.
- Protect resumes, ID scans, and proof documents before uploading them to online application portals.
- Share internal reports, payroll files, or customer lists while limiting copying, editing, and page reordering.
- Let someone read a document without making it easy to print, comment on, or modify it.
- Keep a fillable PDF form usable while locking down the other actions around it.
How to Use
- Upload one PDF file that you want to protect. The current limit is 100MB.
- Enter an open password. If you want a separate password for permission management, expand the advanced options and add it there.
- Choose the print quality and toggle copying, editing, comments, form filling, and page assembly on or off.
- Encrypt the file, download the result, and test the password once before you send it out.
Features
- Browser-side encryption: files stay on your device and are ready to download immediately
- Required open password: recipients must enter a password before they can read the file
- Optional permission password: manage printing, copying, editing, comments, forms, and page assembly separately
- Default AES-128 mode: solid everyday protection with a fallback compatibility mode for older readers
- Simple single-file flow: supports PDFs up to 100MB for contracts, resumes, and scanned documents
When should you use an open password, permission limits, or compatibility mode?
Most people do not need to decide whether to encrypt a PDF. They need to decide whether to lock access only, restrict what happens after opening, or support an older reader.
| Option | Best for | How to set it here | What to know |
|---|---|---|---|
| Open password only | You mainly want to control who can see the file | Enter an open password and keep the default permissions | A practical fit for contracts, quotes, resumes, and similar shared documents |
| Open password plus permission limits | You need to limit access and reduce copying, printing, or editing | Enter an open password and turn off the actions you want to block | Reader apps may enforce limits differently, so this raises the barrier rather than creating perfect protection |
| Compatibility mode | The recipient still uses an older PDF reader | Switch the encryption mode and generate the file again | Use it only when compatibility is the actual problem because it is weaker than the default AES-128 mode |
Best Practices
Remove unnecessary pages before you encrypt
Password protection does not replace content cleanup. If the PDF already includes pages that should never leave your team, remove or extract the right pages first and encrypt the final version only.
Remove PDF pagesExtract PDF pagesStay with AES-128 unless compatibility forces a change
The default mode already covers most day-to-day sharing scenarios and works with modern readers. Drop to compatibility mode only when an older reader cannot open the result.
Adobe Acrobat password security guideSend the file and the password through different channels
Do not place the password in the same email, chat message, or shared folder note as the PDF. Splitting them across two channels lowers the chance of a single leak exposing everything.
Test the result and check the attachment size before sharing
Open the encrypted file yourself once to confirm the password and permissions. If the attachment is still too large, compress the PDF before you send it so it is less likely to fail on email or form uploads.
Compress PDFFAQ
How do I add a password to a PDF?
Upload the PDF, enter an open password, choose the permission restrictions you want, and start encryption. This page handles one file at a time, which makes it easier to double-check the final settings for each document.
What is the difference between the open password and the permission password?
The open password controls whether someone can open the file at all. The permission password controls whether they can print, copy, or edit it after opening it. If you only need to lock access, the open password is enough. Add a separate permission password when you need finer control.
Will PDF encryption change the layout or content?
No. The tool adds password protection and permission flags to the existing PDF, but it does not rewrite the page order, text, or layout. You download an encrypted version of the same document.
Why can someone still copy or print the PDF in some cases?
PDF permission limits depend on whether the reader respects the standard. Adobe Acrobat and major browser readers usually do, but some third-party tools ignore those flags. Use permissions to raise the barrier, not as an absolute content lock.
What should I do if the recipient cannot open the encrypted PDF?
First confirm that the password is correct. Then make sure the recipient is using a modern PDF reader. If an older reader cannot open the default output, create a compatibility-mode version and send that instead.
Are files uploaded to a server?
No. Encryption happens in the browser, so files and passwords do not leave your device. After processing, download the protected PDF right away and send the password through a separate channel.
Can I password-protect several PDFs at once?
Not on this page. It processes one PDF at a time, which is safer when each file needs its own password and permission review. If you have several documents, protect them one by one so you do not apply the wrong settings across the whole batch.
Can I recover a forgotten password later?
No. PDF password protection does not include a recovery path. Test the password before sharing the file, and store it in a trusted password manager or internal key-handling process.
Troubleshooting
The password is rejected even though I entered it
Check capitalization, spaces, keyboard layout, and whether the recipient is opening the exact file version you sent. If you changed the password and generated a new file, the old password will no longer work.
The encrypted PDF does not open in an older reader
Ask the recipient to try Adobe Acrobat, Chrome, or another modern PDF reader first. If their environment cannot change, generate a new copy in compatibility mode.
Copying or printing limits do not fully work
That usually means the reader app is not enforcing the PDF permission flags strictly. For high-value files, combine encryption with tighter sharing control, watermarks, or page cleanup to lower the leak risk.
I still need to edit the document before locking it
Finish page removal, splitting, merging, or watermarking before you encrypt the final version. That avoids repeated decrypt-and-resend cycles later.
Glossary
- Open password
- The password recipients must enter to open the PDF. This tool requires it before it can create the protected file.
- Permission password
- A separate password used to manage restrictions such as printing, copying, and editing. You can set it manually in the advanced options or rely on the open password for basic protection.
- AES-128
- The default encryption mode in this tool. It balances security and reader compatibility for most contracts, resumes, ID scans, and everyday business documents.
- RC4-128 compatibility mode
- A fallback option for older PDF readers. It is less secure than the default AES-128 mode, so use it only when compatibility is the real issue.
- PDF permissions
- Reader apps use permission flags to decide whether printing, copying, editing, commenting, form filling, or page assembly is allowed. Different readers may enforce those limits differently.
Encryption modes available in this tool
Keep the default mode unless you are solving a reader compatibility problem.
| Mode | PDF version | Best for | Notes |
|---|---|---|---|
| AES-128 | PDF 1.6 | Modern readers, contracts, resumes, reports | Default mode with the best balance of protection and compatibility |
| RC4-128 compatibility mode | PDF 1.4 | Recipients who still use older PDF readers | Only use this when compatibility is a real issue because it is weaker than the default mode |
Permission switches at a glance
Choose which actions the recipient still needs after opening the PDF.
| Permission | What happens when you limit it | Typical use |
|---|---|---|
| Print quality | You can reduce printing to a lower quality output | Shared drafts, reviews, external handouts |
| Copy text | Reader apps should block direct text copying | Quotes, report summaries, internal notes |
| Edit content | The file should resist direct text and object edits | Approved contracts and signed-off versions |
| Add comments | Readers should not be able to add annotations | Final versions that are no longer under review |
| Fill forms | You control whether recipients can still type into form fields | Templates, acknowledgements, application forms |
| Page assembly | Readers should not insert, remove, rotate, or reorder pages | Contracts, reports, and manuals with a fixed page sequence |
Privacy & Security
Encryption runs in your browser. Files and passwords are not uploaded to a server. Download the protected PDF right away and send the password through a separate channel.