Drop your document in the emerald zone below, choose what a reader is allowed to do with it, and set a password. The file is encrypted with AES 256, the cipher published by NIST as FIPS 197 and approved for United States classified material up to Top Secret. All of it runs on your own processor. The printing and copying switches are a different thing from the password: they are a request that compliant readers honor, and only the password that stops the file opening enforces anything at all. The document is never uploaded and neither is the password, so nobody here can recover it for you - the honest cost of a lock that works.
Your files are read by JavaScript running on your own machine. There is no upload, no queue, and no copy on our server to delete later.
Drag a card to reorder it, or use the arrows under each card. The order here is the order in the output. Each card is a preview of the finished page, so what you see is what the PDF will contain.
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Starting
This is your processor doing the work, so the time it takes depends on your machine and not on how many other people are on the site.
The encryption tool above is working right now. The guide below explains what a PDF password actually protects you from and what it does not - the difference between the two passwords a PDF can carry, why the permission switches are a request rather than a lock, which cipher to choose when somebody still opens files in Acrobat 8, and how long a determined attacker would take against each one.
It takes about a minute and needs no account for a first run. This PDF password protection tool runs inside the page you are reading, on your own machine. The document is never uploaded and the password is never transmitted, which you can confirm by pulling your network connection out and running it anyway.
Drop the PDF into the zone above or click to pick it from disk. The card reports its page count so you can confirm you grabbed the right file. Only one document at a time: encryption is a decision you make about a specific file, and batching it is how the wrong password ends up on the wrong contract.
Open More settings in the rail and switch printing, copying, editing, commenting, form filling and page assembly on or off. Read the section on permissions below before you rely on any of them - they are recorded in the file as a request to the reader, and the password is the part that actually stops anybody.
Leave it on AES 256 unless you know the recipient opens files in software older than Acrobat 9 or Office 2010. AES 128 covers most of that older population. RC4 128 exists only for genuinely ancient readers and is broken well enough that treating it as security would be a mistake.
Press Protect PDF and a dialog asks for the password twice, with a strength readout beside it. Write the password down somewhere before you confirm. Nothing about it leaves this tab, there is no copy of it anywhere, and a forgotten AES 256 password means a permanently unreadable file - which is precisely the property you are buying.
The download is an ordinary PDF file that any reader will prompt for a password before opening. There is no companion file, no key to keep, and no service that has to stay online for it to keep working in five years.
This is the single most useful thing on this page, and almost nothing that offers to password protect a PDF explains it. The format defines two separate passwords with two completely different jobs.
That second one is why so many people arrive at a PDF password remover asking why the document opened instantly but would not let them print. It was never locked. It was labeled.
If the document must not be readable by the wrong person, set the open password. An owner password alone is removed by any of a hundred free utilities in one click, including the one on this site, because removing it requires no secret at all. It is a lock with the key taped to it.
It has one honest use: stopping a colleague from doing something by accident. A price list that must not be edited by the sales team, a form that must not have its pages reordered, a report that should be read rather than copied and pasted into somebody else's deck. Every one of those is a case where the reader is not an adversary and a polite refusal is enough. Use it to prevent mistakes, never to prevent access.
The tool above sets both. If you leave the separate owner password switch off, the two are the same string, which is the right default: an owner password of nothing is an owner password anybody can strip. Turn the switch on and you get a document that opens with one password and reconfigures with another, which is what you want when a file is shared with a team but administered by one person.
When you set a password, three things are computed and written into the file. Understanding them is what tells you how much protection you actually bought.
Everything that matters is in step two, and it is where the three cipher choices differ enormously - far more than the cipher name suggests.
| Setting | Key derivation | What a modern machine achieves | Use it when |
|---|---|---|---|
| AES 256 (revision 6) | Algorithm 2.B: at minimum 64 rounds of AES over a buffer 64 times the password length, hashed each round with SHA-256, SHA-384 or SHA-512 depending on the previous round's output. | A few thousand password guesses per second. A random 12 character password is out of reach of anybody who is not a state. | Always, unless you have a specific compatibility reason not to. |
| AES 128 (revision 4) | MD5, iterated 50 times over a 16 byte key. | Tens of millions of guesses per second on one graphics card. A dictionary word with a number after it falls in minutes. | Acrobat 7 or 8 on the far end, or a document management system from the same era. |
| RC4 128 (revision 4) | The same weak MD5 derivation, feeding a stream cipher with known statistical biases. | The same weak derivation, plus a cipher nobody has recommended since 2015. | Genuinely ancient readers only. Treat it as a seal on an envelope, not a safe. |
AES 128 has never been broken, and the cipher is almost never the part an attacker goes after. What separates the top row from the other two is the deliberate slowness of the key derivation. Algorithm 2.B exists purely to make guessing expensive, and it succeeds by four orders of magnitude: tens of millions of guesses a second on a graphics card become a few thousand. That is why the default here is AES 256, and why the interface tells you plainly when you pick something else.
Encrypting a stream changes its length. AES adds a 16 byte initialization vector and pads the data to a block boundary, so every stream in the document grows. A PDF is indexed by byte offset, so the moment one stream changes size, every offset after it in the cross-reference table is wrong. The engine therefore reads every object out of the file, encrypts it, and writes a completely new document with a freshly measured index. That is also why the output is byte for byte a new file rather than a patched copy of the original.
The rail lets you deny printing, copying, editing, commenting, form filling and page assembly. Here is exactly what happens to each of those instructions, because the marketing language around this feature is close to dishonest across the whole category.
Those six switches are written into the document as a single 32 bit integer, in the clear, next to the encryption details. A reader looks at that integer and decides whether to grey out the print button. Nothing stops a reader from ignoring it. Several do. Plenty of command line tools do not even look.
Permissions are a request. The open password is enforcement. If your threat model includes somebody who does not want to respect the rules, the only switch on this page that matters is the one that stops the file opening at all.
Extraction for accessibility - the flag that lets a screen reader read a document aloud to somebody who cannot see it - was deprecated in ISO 32000-2 and is ignored by every current reader. This tool always grants it and does not offer a switch, because offering one would be theatre. A document that a blind colleague cannot read is not a secure document, it is an inaccessible one.
The format distinguishes between printing at all and printing at full quality, the latter being a hangover from an era when the low quality option produced a deliberately degraded raster. It is close to meaningless now, so the tool treats them as one setting. Turn printing on and you get both.
| Switch | What a compliant reader does | What it does not do |
|---|---|---|
| Allow printing | Greys out the print command and refuses to render to a printer or a virtual PDF printer. | Stop a screenshot, a phone camera, or a reader that ignores the flag. |
| Allow copying | Disables select and copy, and blocks text extraction in most viewers. | Stop text extraction by any tool that reads the content stream directly. |
| Allow editing | Refuses to save changes to the page content. | Stop a tool that rewrites the file without asking the flag. |
| Allow comments | Blocks new annotations and mark-up. | Remove annotations that are already in the document. |
| Allow form filling | Makes fields read-only. | Stop the underlying field values being read. |
| Allow page assembly | Refuses insert, delete, rotate and reorder. | Stop a merge tool that copies pages into a new document. |
One protection here is real. In AES 256 the permission integer is also stored a second time, encrypted with the file key, in a field called Perms. A reader that decrypts that copy and finds it disagrees with the plaintext one knows the file has been tampered with. It does not stop a determined attacker, and it does mean the permissions cannot be quietly edited by somebody who does not hold the password.
This matters more here than it does on a website login, and for a reason worth stating plainly. When you log in somewhere, a server rate limits the attempts. Ten wrong guesses and it locks you out. An encrypted PDF has no server: the attacker has the whole file, offline, and can guess as fast as their hardware allows, forever.
So the only thing between your document and a patient attacker is how many guesses it takes. Which means length, and variety, and nothing else. The strength meter in the dialog measures exactly that and ignores the rules that produce Passw0rd!.
There is no recovery, and that is the feature. The password is never sent anywhere, so there is nothing here to reset. If the encryption were recoverable by us it would be recoverable by anybody who compromised us, and the guarantee on this page would be worthless. Write it down before you press the button.
Every competing tool that offers to encrypt a PDF online asks you to upload it first. Think about what that means for thirty seconds. To put a password on a confidential document, you first send that document, unencrypted, over the internet, to a machine you do not control, run by people you have not met, where it sits on a disk while a queue processes it. The one moment the file is most sensitive is the moment they ask you to hand it over.
This tool does the work where the file already is. The cipher, the key derivation, the random number generation and the file rewriting are all JavaScript running in your tab, using your processor. There is no upload endpoint for the document because there is no server side to this operation.
The verification is trivial and you should do it. Load this page, turn off your wifi, and encrypt a document. It works. An upload based tool cannot do that, and no amount of privacy policy changes the difference.
AES 256 with revision 6 was standardized in PDF 2.0, published as ISO 32000-2, and mainstream software has supported it for well over a decade. In practice the file opens everywhere that matters:
The population that genuinely cannot open it is small and specific: Acrobat 8 and older, some embedded viewers in older document management systems, and a handful of industrial or point-of-sale devices. If the recipient is in that group, AES 128 covers almost all of them and is still a real cipher. RC4 is the last resort and the interface says so when you pick it.
Test before you send, once. Encrypt a throwaway document with the setting you plan to use and open it on whatever the recipient actually uses. Ten minutes now beats a phone call that starts "it says the file is damaged" on the day of a deadline.
Every tool in this suite carries this section. Here is what this one cannot do.
And one thing worth repeating because people get it backwards: a password on a PDF protects the file, not the information. Once the recipient opens it, they have the contents and can do anything they like with them. Encryption protects a document in transit and at rest. It does not protect it from the person you sent it to.
A few patterns that come up constantly, with the order of operations that avoids doing the work twice.
| What you are sending | Sensible order |
|---|---|
| Payroll or an invoice batch | Merge the pages, strip the metadata, then encrypt. Encrypt last, always: every other tool has to read the file, and an encrypted file is one nothing can read. |
| A signed contract | Sign it first with Sign PDF, then encrypt. Encrypting after signing preserves the signature; editing after signing breaks it. |
| A document with something removed | Redact with Redact PDF, confirm the text is genuinely gone, then encrypt. Encryption over an unredacted document just hides the leak behind a password somebody has. |
| A scan for an archive | Run OCR PDF so it is searchable, then encrypt. Encrypting first makes the scan unreadable to the text recognizer. |
The rule underneath all four rows is the same. Encryption is the last thing you do to a document, because it is the thing that makes every other operation impossible. The rest of the PDF suite follows the same architecture as this page: nothing uploaded, nothing stored, everything on your own machine.
Drop the file into the zone at the top of this page, choose what a reader may do with it, and press Protect PDF. A dialog asks for the password twice and the encrypted file downloads immediately. No account is needed for a first run, nothing is uploaded, and no watermark is added. The whole operation runs on your own processor inside this browser tab.
No. The document is read from your disk by the browser, encrypted in memory, and written straight back to your downloads folder. The password is never transmitted either. You can verify this by disconnecting from the internet after this page has loaded and encrypting a file anyway - it works, which no upload based tool can manage.
The user password stops the document opening at all: without it there is nothing to read. The owner password does not stop the file opening - it only sets what a reader is permitted to do, such as printing or copying. An owner password alone is removed by any free tool in one click, because removing it needs no secret. If the content must be private, set the user password.
No, and nobody else can either. The password is never sent anywhere, so there is nothing to reset. The file is encrypted with AES 256 and the only way in is the correct password. That is the entire point of the tool - a lock we could open on request would be a lock anybody who compromised us could open. Write it down before you encrypt.
AES 256 unless you have a specific reason not to. Its key derivation is deliberately slow, which cuts an attacker from tens of millions of guesses a second to a few thousand. AES 128 uses a much weaker derivation and exists here for Acrobat 7 and 8. RC4 128 is for genuinely ancient readers and should be treated as a seal rather than a lock.
Yes. AES 256 encrypted PDFs open in the built-in viewers on iOS and iPadOS, in Google Drive and Adobe Reader on Android, and in Chrome, Safari, Firefox and Edge on any platform. Each one prompts for the password before displaying a single page.
Partly, and it is worth being precise. Those permissions are stored in the file in the clear, as a request to the reader rather than as enforcement. Compliant software honors them. Software that chooses not to can ignore them entirely, and a document carrying only an owner password is stripped in one click by dozens of free utilities, including the Unlock PDF tool on this site. Use the permission switches to stop colleagues doing things by accident. Use the open password to stop anybody who does not want to be stopped.
Not directly, and the tool refuses rather than producing a broken file. Encrypting an already encrypted document creates something no reader can open. Remove the existing protection with Unlock PDF first, using the password you have, then set the new one here.
The password decides it, not the cipher. Against a random twelve character password, longer than any organization will fund. Against a dictionary word with a year after it, a few hours on one graphics card. The password has always been the weak point. Four random words is a better answer than eight characters of punctuation, and it is far easier to type into a phone.
No. Every page, font, image and vector is identical - they are the same bytes, stored encrypted. Once the reader has the password, the document renders and prints exactly as it did before. File size grows by roughly one to two percent because each stream carries an initialization vector and padding.
Not in one run, deliberately. Encryption is a decision about a specific document and a specific password, and batching it is how the wrong password ends up on the wrong file with nobody noticing until it matters. If several documents genuinely need the same password, merge them first and encrypt the result.
Encryption at rest and in transit is one control among several, and AES 256 is a recognized standard for it. On its own it is not a compliance program. How the password is shared, who holds it, and what happens to the document after somebody opens it all matter more than the cipher. Ask whoever owns your policy, not a tool page.
No. The output is your document, encrypted, and nothing else. No stamps, no banners, no attribution link. If you want a watermark on a document, that is a deliberate choice you make with Add Watermark before you encrypt.
No. A visitor who is not signed in gets one operation every twelve hours, counted by network fingerprinting. A free CartHacker account raises that to two in the same twelve hour window, and CartHacker Premium removes the limit. None of those tiers change what happens to your file - the encryption is identical and local in every case.
All of these run the same way: your file is read by JavaScript on your own machine, the work happens on your processor, and the result is handed back to you as a download that never existed anywhere else.
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