BASALT · JOURNAL
How to remove a password from a PDF you are allowed to open
Removing a password from a PDF is straightforward when you know the password and impossible when you do not. Everything confusing about this topic comes from tools that blur that line.
This post covers what removal does to the file, the two kinds of password you might be removing, and what it means when a website offers to unlock a document you cannot open.
What removal actually means
An encrypted PDF stores its streams and strings as ciphertext, with an encryption dictionary in the trailer describing the algorithm, the key length, the permission bits, and the values used to check a supplied password. Removing the password means decrypting every one of those streams and strings, writing them out in the clear, and dropping the encryption dictionary. The result is a normal unencrypted PDF with identical page content, which anyone who obtains the copy can read.
This requires the decryption key, which is derived from the password. Not from the file, not from the permission flags, not from anything an application can compute on its own. If you cannot supply the password, no legitimate tool can produce the plaintext.
Two removals, two different situations
Removing a user password. The user password is the open password, and you already had to type it to see the document. Removal takes that same password, derives the key, decrypts, and writes an unencrypted copy. This is the case people usually mean: a bank statement or payroll PDF that prompts for a code every single time you open it.
Removing an owner password. An owner password sets permission flags without requiring anything to open the file. Because such a document opens for everyone already, the practical effect of removing it is only to clear restriction bits that mainstream readers voluntarily honor. This is not a security operation in either direction, as covered in what a PDF password actually does.
The honest position on files you cannot open
If you do not have the password to a PDF, there are exactly two things that can happen, and both should be named plainly.
Someone can attempt to guess it. That is password cracking: trying candidates against the file's verification value until one derives a working key. Against AES-256 with modern key derivation and a decent password, this fails, in the sense that it does not finish. Against a short numeric password, or one built from a date of birth or the last digits of an account number, it can succeed quickly. That is a property of the password, not of the tool.
Or your file gets uploaded. A browser page that promises to unlock any PDF is sending your document to a server, so the untreated original has left your machine for infrastructure you cannot inspect, with retention terms you probably did not read. For a payroll file, a medical record, or anything under a protective order, that transfer is the actual event, and it is worse than the inconvenience you were trying to solve. The exposure model is worked through in the risk in cloud PDF tools.
There is no third option where software mathematically undoes AES because it is clever. Any product implying otherwise is doing one of those two things and describing it euphemistically. Basalt has no cracking mode: if you supply the password it decrypts and writes a clean file, and if you do not, it says so and stops.
Getting the password rather than defeating it
For the documents people most often want unlocked, the password is usually obtainable. Bank and card statements are commonly encrypted with a derived password documented in the issuer's own email or help pages: a customer ID, a date of birth in a stated format, a combination of name and account digits. Read the covering message, because it is nearly always written down there.
Payroll and HR files typically use a scheme set by whoever generated them, and that person can tell you. Documents received in discovery come with a producing party who can be asked, and that request is routine and creates a record. If the password is genuinely lost, ask whoever issued the file to reissue it.
After removal
A decrypted copy is a plaintext document, readable by anything with filesystem access, indexed by Spotlight, and synced to whatever cloud folder it lives in. Put it somewhere consistent with how sensitive it is.
Decryption also does not remove anything. Metadata, XMP history, form field values, annotation authors, and any text under a black rectangle survive intact, because they were only ever encrypted, not deleted. If the plaintext copy is going anywhere, cleanup and redaction are separate work, covered in removing metadata from a PDF and permanently deleting text from a PDF.
Frequently asked questions
How do I remove a password from a PDF on a Mac?
Open the file with the password, then use a PDF tool's remove password function to write a new decrypted copy. In Preview you can open the document with its password and export it as a new PDF without encryption enabled, which produces an unprotected file. Every legitimate method requires you to supply the password first, because the decryption key is derived from it and cannot be recovered from the file.
Can I remove a PDF password without knowing the password?
No, not by any legitimate method, because the decryption key is derived from the password and exists nowhere in the file. The only alternatives are guessing the password, which succeeds only against weak ones, or uploading the document to a service that attempts it for you. If the document matters, ask whoever issued it to resend or reissue it rather than pursuing either route.
Are online PDF unlockers safe to use?
No, because using one means uploading the complete document to a third-party server. You cannot see what happens to the file afterward, how long it is retained, or who has access, and for anything covered by privilege, HIPAA, GDPR, or a protective order that upload is itself the problem. The inconvenience of typing a password is smaller than the exposure of transmitting the document.
Does removing a password change the content of the PDF?
No, decryption produces an identical document with the ciphertext replaced by plaintext, so every page, image, font, and annotation is exactly as it was. What changes is that the file no longer requires a key to open. Metadata, form values, and hidden content are all still present, since they were encrypted rather than removed.
Why does my bank statement ask for a password every time?
Because it was issued with a user password, the open password required to decrypt the document, and that requirement is stored in the file itself rather than in your reader. The password is usually a derived value documented in the email that delivered the statement, such as a customer ID or a date of birth in a stated format. Once you know it, you can write an unencrypted copy.
What is the difference between removing a password and cracking one?
Removing a password means supplying the correct password, deriving the key, and writing a decrypted copy, while cracking means guessing candidates until one works. The first is a normal file operation that takes moments; the second is a search whose success depends entirely on how weak the password is. Tools offering to unlock files you cannot open are doing the second.
Can Basalt crack a PDF password?
No, Basalt has no cracking mode and will not guess passwords. Its password tool removes encryption only when you supply the correct password, and otherwise reports that it cannot open the document and stops. This is deliberate: the alternative would either be an offline guessing engine or an upload, and neither belongs in a tool built to keep documents on the machine.
Doing it in Basalt
Basalt removes a password when you supply it, writing a new decrypted file and leaving the encrypted original exactly as it was. There is no cracking mode and no guessing, and the engine runs in a process with no network entitlement, enforced by macOS at the code-signature level, so nothing is uploaded. The same window also adds passwords, redacts with a verifier that proves the content is gone, strips metadata, and flattens forms. It is $29 once for up to three Macs, free for 24 hours, at basaltformac.com.
Redaction that proves itself
Basalt destroys the content you mark, then re-opens the file it wrote and proves the content is gone before it saves anything. Your documents never leave your Mac.