Protect PDF Document

Encrypt your PDF with a password to restrict access. All processing is completed locally in your browser memory.

Select PDF file

or drag and drop PDF here

0%

Encrypting PDF

Applying password security...

Secure PDF Protection: Password Lock Documents Locally in Your Browser

Standard cloud lockers require uploading unencrypted PDF archives to their remote environments to append key locks. This poses security and compliance risks. Document Alter executes cryptographic operations directly inside your browser's memory context.

Client-Side Cryptographic PDF Salting

The tool processes your document byte stream locally, combining your custom user password with encryption hashes using @pdfsmaller/pdf-encrypt-lite. The security parameters are compiled directly into the PDF's header catalog metadata dictionary, ensuring robust lock integrity.

How to Password Protect a PDF (Step-by-Step Guide)

1

Upload PDF Document

Drag and drop the target PDF you want to protect into the secure dropzone.

2

Set User Password

Enter your chosen password in the input field within the settings sidebar.

3

Download Secure PDF

Click the 'Encrypt PDF' button to run encryption routines locally and save your password-locked file.

Frequently Asked Questions

Document Alter encrypts your PDF files in your browser using local WASM and JavaScript modules. The encryption process applies user password protection locally, generating a standard secured PDF binary.

Yes. Since the password protection runs completely client-side in browser RAM, your password and your files are never transmitted over the internet or saved on any server.

The tool applies industry-standard RC4 128-bit PDF encryption, preventing unauthorized viewers from opening or accessing the vector document stream without the correct user password.