Encrypt PDF / Password Protect PDF
Add a password to your PDF and restrict printing, copying, and editing.
Your PDF and password never leave your browser. All encryption runs locally via pdf-lib (WebAssembly).
Permission restrictions (optional) — ticked = action forbidden
Working...
[ AdSense slot ]
⚠️ If you lose the password, the PDF cannot be opened. Store it in a password manager or another safe place.
When to use this
| Scenario | Recommended settings |
|---|---|
| Confidential company documents | User password + restrict printing & copying |
| Contracts / quotes for review | User password only (read access) |
| Sharing a resume / portfolio | Restrict printing & copying (allow editing) |
| Preserving legal documents | Restrict editing & annotating |
| Student exam papers / answer keys | User password + no printing |
| Prevent catalog copying | Restrict copying (allow read & print) |
Related tools
Security boundaries
When to use it
Contract deliveryNDAs, employment / lease agreements — gate with a password before sending. Block print / copy permissions to deter resharing.
Résumés · cover lettersPassword-protect career history before sending to recruiters / HR. Pass the password by a separate channel.
Invoices · legalTax invoices / legal opinions. Permission flags lock down editing and annotation.
Course materialsPaid course PDFs — block copy / print to deter unauthorized sharing.
Proposals · pitch decksExternal proposals — password + draft watermark + permission limits during negotiations.
Medical · legal recordsPersonal medical records or legal documents — only the owner / authorized parties open.
RC4 128-bit — actual security strength
PDF 1.7 standard encryption (RC4 128-bit). Compatible with Adobe Acrobat, Preview, Chrome PDF, and all standard viewers.
Strengths — adequate for casual permission gating and password protection. Top compatibility.
Weaknesses — late-1990s standard, weak vs modern crypto. For trade secrets / legal evidence / classified data, prefer external zip 7z AES-256 or dedicated DRM.
PDF spec also defines AES-256, but the underlying pdf-lib-plus-encrypt library only implements RC4 128-bit. AES support is on the roadmap.
Permission flags (4)
- Print — blocked unless password is entered (some viewers ignore)
- Copy text — text selection / copy disabled. Screenshot / OCR can bypass.
- Edit — adding / removing / modifying pages disabled
- Annotate — highlights / notes / signatures disabled
contentAccessibility is always true so screen readers can still read the text — accessibility-first design.
Password entry safeguards
- Enter twice + live match — color shifts (green vs red) while typing
- 4 character minimum — rejects trivial passwords
- Show / hide toggle — for visual confirmation
- Already-encrypted PDF detected — explicit alert on re-encryption
- Recovery is impossible — neither this tool nor the operator can recover a lost password. Write it down safely.
Common pitfalls
- Weak passwords (1234 / password) — brute-forced in under a second. Use 12+ chars with letters / numbers / symbols.
- Lost password — no recovery here. No admin / master password.
- PDF + password in same email — defeats the purpose. Send password via a different channel.
- Print restriction bypass — Chrome "Print to PDF" or screenshots can work around it. Treat permissions as honor-system.
- Permission removal tools — public utilities can strip RC4 permission flags. Permissions are first-line defense only.
FAQ
Are my PDF or password uploaded?
No. All encryption runs in your browser via pdf-lib (WebAssembly). The PDF content and password never leave your device — the site operator cannot see them.
What encryption method?
RC4 128-bit (PDF 1.7 standard). Compatible with Adobe Acrobat, Preview, Chrome PDF viewer, and any standards-compliant reader.
What if I lose the password?
Recovery is impossible. The password is used only in the browser and never stored. Store it separately in a password manager.
User vs. owner password?
User password: required to open the PDF. Owner password: required to lift permission restrictions. This tool uses the same value for both.
How strong are permission restrictions?
They rely on PDF viewers voluntarily honoring the flags. Adobe Acrobat, Chrome, Preview all respect them, but some third-party tools can bypass. For real security, also set a user password.
Can I encrypt an already-encrypted PDF?
No. Remove the existing password first. This tool only accepts plaintext PDFs.
Encrypt only PDFs you own
Encrypting someone else's PDF without permission may raise copyright or business-interference issues. Only encrypt PDFs you own or are authorized to modify.
References
Last verified: 2026-05-17 / pdf-lib-plus-encrypt (MIT) WebAssembly.
- pdf-lib-plus-encrypt (MIT) — GitHub
- PDF 1.7 standard — ISO 32000-1, Section 7.6 Encryption
⚠️ Permission flags depend on the viewer's voluntary compliance. For real data protection, set a user password and share via a trusted channel.