VUISO LOCK PDF - how to use =========================== Put a password on a PDF, and choose what someone who has that password may do with it. The file is encrypted inside your browser with AES-256. Nothing is uploaded, there is no account, and it works with the network switched off. Your password is used by the browser and then forgotten. It is never stored, never written to disk and never sent anywhere. READ THE SECTION CALLED "THERE IS NO WAY BACK" BEFORE YOU LOCK ANYTHING THAT MATTERS. This tool works on ONE FILE at a time. OPENING IT Double-click "Vuiso Lock PDF.html". It opens in your browser like a normal page. There is nothing to install. Chrome or Edge is recommended; Firefox and Safari work too. THE SHORT VERSION 1. Open PDF (or drag the file onto the page area) 2. Type a password twice, so a typo cannot lock you out 3. Lock and save Nothing is written until you press the button in the Save window. THE PASSWORD TO OPEN This is the one a reader is asked for when they double-click the file. Type it twice; the two fields turn red if they disagree, and Save stays out of reach until they match. The eye at the end of each field shows what you typed. Use it. A password you cannot read is how people lock themselves out of their own documents. Under the field is a strength bar with four steps. It weighs LENGTH most heavily, because length is what actually matters: very weak under 6 characters, or a short word with no variety weak 8 or more, but little variety fair 12 or more, or 8 or more with three kinds of character strong 16 or more, or 12 or more with two kinds A good password here is four unrelated words you can remember, such as "cement harbour violin pencil". It is far harder to guess than "P@ssw0rd!" and far easier to type. The encryption itself is as strong as a PDF can carry, so the password is the only part of this that can be weak. WHAT THE READER MAY DO Eight things can be allowed or denied. All eight start out allowed, and "Allow all" / "Allow none" set them in one go. Print printing the document at all Print at full quality printing from the real pages rather than from a coarse copy. Goes quiet when Print is off, because it means nothing then Copy text and pictures selecting the contents and pasting them out Change the contents editing the text and pictures on a page Add, remove or rotate pages rearranging the document Comment and mark up notes, highlights, stamps Fill in form fields typing into a form, without altering the form Read aloud by a screen the text being handed to assistive software reader Leave the screen reader box ON. Turning it off is allowed by the PDF format and blocks the tools blind readers depend on. "Allow none" deliberately leaves it alone; you can still turn it off yourself if you truly mean to. BE HONEST WITH YOURSELF ABOUT WHAT THESE ARE. They are requests written into the file. Every serious PDF reader honours them, and a program that chooses not to honour them can ignore them completely, because the contents are encrypted and the restrictions are not. They stop the ordinary reader doing something by accident. They do not stop somebody determined. The one real wall is the password. Without it, the contents cannot be read at all, by any program. THE OWNER PASSWORD Under "Owner password", which starts collapsed, is a second password that LIFTS the restrictions above. By default it is the same as the password to open, which is what most people want. Set it separately when you want to hand a file out and keep control of it: give readers the first password, keep the owner password to yourself, and they can open the document but not, say, print it - while you still can. It cannot be the same as the password to open. If it were, the two would be indistinguishable and the restrictions would apply to nobody. Inside that block is one more choice: Let anyone open the file No password is asked for on opening. Anybody can read the document; the restrictions still apply, and only the owner password lifts them. Use it for something you want freely readable but marked "do not print". It is not privacy: the file opens for everyone. The Save window says so. THERE IS NO WAY BACK If you lose the password, the file is lost. Not difficult - lost. - Vuiso never sees your password. It is typed into a page that cannot open a network connection. - Nothing is stored. There is no copy on your computer, in the browser, or anywhere else. - There is no reset, no recovery code and no back door. Asking us will not help, because we have nothing to give you. - AES-256 cannot be brute-forced by anyone, and that includes you. Write the password down somewhere safe, or put it in a password manager, BEFORE you press Save. Keep the original unlocked file as well, at least until you have opened the locked copy and typed the password successfully. SAVING "Lock and save" shows a summary first: the source file, the encryption, which passwords are set, what is not allowed, and the output name. Nothing is written until you press the button in that window. The copy is named " - locked.pdf". Your original file is never modified. Locking takes a moment on a big file: every stream and every string inside the document is encrypted separately, and the progress window counts them. CHECKING THE PAGES Click any page to see it large. Zoom in doubles it, Left and Right move between pages, Esc closes it. This shows the file you opened, which is also the file you are about to lock - locking changes nothing about how a page looks. KEYBOARD SHORTCUTS Ctrl+O Open PDF Ctrl+E Lock and save Enter in a password field: lock and save Left / Right previous and next page in the large view Esc close the large view, or the Save window WHAT COMES OUT A PDF with the standard security handler, revision 6: AES-256 in CBC mode, the strongest encryption the PDF format defines, introduced in PDF 2.0 and read by Acrobat, Chrome, Edge, Firefox, Preview on macOS, and every current PDF library. The document's own metadata is encrypted along with its contents. Very old software may not understand it. A reader from before roughly 2009 can be expected to refuse the file rather than open it, which is the right way round: it fails loudly, not quietly. NOTES - A PDF that is ALREADY locked cannot be opened here. The tool says so and tells you what to do: open it in a reader, save an unprotected copy, and lock that copy. This tool adds protection; it does not remove it. - A digitally SIGNED PDF can be locked, but the signature will break. Locking writes a new file, and a signature signs the exact bytes of the file it was made in. The Save window warns you when it sees one. - How long it takes depends on the number of objects in the document rather than on its size in megabytes: a 40-page report with many small streams can take longer than a 6MB scan of four pages. - Nothing is stored. No cookies, no database. The only thing remembered is which of the two languages you chose. In particular, no password is remembered - close the tab and it is gone from the tool for good. - The tool needs the browser's own encryption (WebCrypto), which every current browser has, including when this file is opened from your disk. If a browser does not offer it, the tool says so and refuses rather than producing a file that looks locked and is not. PRIVACY The file contains a Content-Security-Policy that forbids network connections entirely. That is enforced by the browser, not promised by us: open DevTools, watch the Network tab, and it stays empty while you type your password and lock your file. You can also disconnect from the internet and the tool still works. Verify the copy you hold matches the one published: Windows Get-FileHash "Vuiso Lock PDF.html" -Algorithm SHA256 macOS/Linux shasum -a 256 "Vuiso Lock PDF.html" Compare the result with the SHA-256 printed on the download page and in the .sha256.txt file next to this one. For a tool that handles passwords this is worth doing rather than skipping. LICENCE See LICENSES.txt, which must stay alongside the tool.