解除 PDF 保护
去掉你已知道的密码，或去掉根本不需要密码的限制。
这款工具完全在你的浏览器中运行。文件从不上传，你可以在浏览器的网络标签中亲自验证这一点。 亲自验证：打开浏览器的网络标签观察。你会看到一个查询你是否还有剩余任务的小请求，只包含工具名称和一段哈希，绝不会包含文件。
这款工具的作用
This removes a PDF's encryption and its restriction flags and writes a plain document you can merge, print, edit or copy from like any other. It does not guess passwords. If the file needs one to open, you have to know it - a line this tool will not cross, stated here rather than discovered halfway through.
Two situations. A file that opens for everybody but declares that it may not be printed or copied, which is how documents arrive from banks, government portals and print shops all the time. Or a file you do have the password for and are tired of typing: an archived statement, a payslip encrypted by an employer's policy, a contract you need to fold into a bundle.
工作原理
- Drop the PDF onto this page. It is inspected first, so you are told whether the document is genuinely encrypted or only carrying restriction flags.
- If it opens without a password, leave the password box empty - owner restrictions come off with nothing typed at all.
- If it asks for a password to open, type it. It is used inside your browser and is neither stored nor sent.
- Press Unlock PDF. A file that is not protected in the first place is refused rather than copied.
- The download starts on its own. The result opens with no password and carries no restrictions.
A permissions-only PDF is encrypted, but with an empty user password, which means every reader can already derive the key and open it. The restrictions ride along as flags rather than as cryptography. That is why removing them needs nothing from you: the lock was never locked, and the tool writes the document out again with no security handler on it.
There is no password recovery here and there will not be. Recovering a password nobody has is what a cracking tool does, and shipping one inside a privacy tool would make this a different product with different visitors. If you have lost the password to your own document, the realistic options are an earlier copy, a backup, or whoever sent it.
The advanced toggle that leaves a permissions layer in place is a narrow thing, for archives whose policy expects every file to carry a security handler. It rewrites the result with empty passwords, so the document still opens for anybody. It does not reinstate the restrictions the original carried: the permissions come back at their defaults, which allow everything.
Unlocking is usually a step rather than a destination. Merging, splitting and page editing all need to read the page objects, which encryption prevents, so a locked file fails those tools with an error pointing back here. The password itself never leaves your machine, including on a failed attempt.
这款工具做不到的事
- It cannot open a document whose password nobody knows. There is no recovery, no guessing and no wordlist.
- A file that is not encrypted at all is refused rather than copied, so you never get back something you cannot tell apart from the file you dropped in.
- The option that leaves a permissions layer in place does not restore the original restriction flags; it writes a fresh empty-password layer whose permissions allow everything.
常见问题
- 我忘了密码，这个能打开吗？
- 不能。文档确实被加密，它的密钥由密码推导而来，没有密码就无从下手。这个工具不会尝试各种组合，将来也不会。如果你的文件能正常打开、只是拒绝打印或复制，那你根本不需要密码。
- 我的 PDF 能正常打开，却不让打印或复制。这是什么？
- 所有者限制。文档是用空的用户密码加密的，所以谁都能打开，而打印和复制的规则只是阅读器自愿遵守的标志。去掉它们不需要你提供密码：把输入框留空，然后解除保护即可。
- 我输入的密码会去哪里？
- 哪里都不去。它被交给以 WebAssembly 形式在你浏览器 worker 里运行的 qpdf，用来推导密钥，任务结束时丢弃。它不会被保存、记录或发送。想看它一直安静，可以先打开网络面板。
- 去掉 PDF 的保护合法吗？
- 从你拥有或有权使用的文档上去掉限制是很平常的事，这个工具就是为此而生。闯入别人专门对你加密的文档则不是，而且这个工具也帮不上忙，因为它需要密码。
- 文件会被上传吗？
- 不会。无论是告诉你面对哪种保护的检查，还是解密本身，都在你的浏览器里进行。任何环节都不发送任何东西，包括密码输错时；页面加载之后，工具还能离线继续工作。