What does Protect PDF do?

It encrypts a PDF with a password so it can’t be opened without entering the correct password. You can set both an open password and a separate owner password for controlling edit/print permissions.

Is my PDF uploaded to a server?

No. Encryption runs entirely in your browser. Your file and password never leave your device.

What’s the difference between a user password and an owner password?

The user password is required to open the file. The owner password controls what viewers can do — printing, copying text, editing. If you only set a user password, the owner password defaults to the same value.

Can I encrypt a PDF that’s already password-protected?

Yes. You’ll enter the current password to decrypt it first, then set a new password. Everything happens locally.

How strong should my password be?

The tool shows a strength indicator. Use at least 8 characters with a mix of letters, numbers, and symbols. A weak password undermines the encryption no matter how good the algorithm is.

What encryption standard is used?

The tool uses standard PDF encryption. The resulting file is compatible with all major PDF readers including Adobe Acrobat, Preview, and Chrome’s built-in viewer.

PDF保護（パスワード設定）

PDFをパスワードで暗号化して保護します。

1. Select PDF

Select a PDF file from your device. All processing happens locally in your browser.

2. Set password

Enter a strong password to encrypt your PDF. Use a mix of letters, numbers, and symbols.

3. Download

Get your protected PDF instantly. The file will require the password to open.

About Protect PDF

How PDF Encryption Works

You pick a password. The tool encrypts the entire PDF so that anyone who tries to open it gets a password prompt first. No password, no access. The encrypted file downloads to your device, ready to share.

OxygenPDF supports both a user password (required to open the file) and an owner password (controls editing and printing permissions). If you only set one, both default to the same value.

When You Need to Protect a PDF

Any document that would cause problems in the wrong hands is a candidate for password protection.

Confidential Reports

Financial statements, audit findings, internal memos. Add a password before emailing so only the intended recipient can read them.

Legal Documents

Contracts, settlement agreements, court filings. Encryption adds a layer of access control when sharing sensitive legal files.

Tax & Financial Records

Tax returns, bank statements, payroll data. Password protection is the minimum before sending these to an accountant or advisor.

HR & Personnel Files

Employee records, performance reviews, offer letters. Encrypt before storing in shared drives or sending over email.

How It Compares

Most PDF tools offer encryption, but the details matter: where the encryption happens, what algorithm is used, and whether your file gets uploaded.

機能	Adobe Acrobat	iLovePDF
User password (open)
Owner password (permissions)
Password strength indicator
Encryption happens locally	Desktop only
No file upload required	Desktop only
Free to use		Limited

Encryption Happens on Your Device

The whole point of encrypting a PDF is to keep its contents away from unauthorized eyes. Uploading it to a server for encryption defeats the purpose — you’re handing the unencrypted file to a third party before they lock it for you.

OxygenPDF encrypts the PDF in your browser. The file doesn’t leave your machine. Your password never leaves your machine. The encrypted result is produced locally and downloads straight to your device.