ConvertWarp

Protect PDF

Add a password that is required to open the PDF. This is not a certificate.

Password protection uses pdf-lib-encrypt (MIT) and pdf-lib (MIT).

About this tool

Protect PDF adds an AES-256 open password: a reader must type it before the file opens. It is not a digital certificate, not a permission-flag circus, and not a promise that every viewer on earth implements encryption the same way.

Use at least four characters. Remember the password; ConvertWarp never sees it and cannot reset it. Unlock PDF is the inverse if you already know the password.

The file is encrypted in the browser with pdf-lib-encrypt. 50 MB. Some already-odd PDFs (certain object streams, AES-128 variants) may refuse. This requires a secure context (HTTPS or localhost).

How to password-protect a PDF

  1. Choose an unlocked PDF. The open password is set in this tab.
  2. Enter a password of at least four characters.
  3. Protect and download the locked PDF.

50 MB. Open password only. AES-128 files and some compressed-object constructs may not lock. Not a certificate.

FAQ

Do you receive the password or the PDF?
No. Encryption runs in this tab. We cannot recover a forgotten password.
Is this legally equivalent to a qualified signature?
No. It is an open password. Sign PDF is also not a certificate — it is a picture.
Can I set print-only permissions?
Not in v1. Permission flags are not treated as a real lock here.
Why did a file fail?
Some protection modes and object streams are unsupported in the browser build. The error text says so instead of uploading to a server that might handle them.
HTTPS required?
Web Crypto needs a secure context. Localhost during development counts.

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