如何在线给 PDF 加密 — 免费指南
通过设置打开密码，PDF 加密可以防止未经授权的访问。除了打开密码外，你还可以独立限制打印、复制和编辑权限。无需安装 Adobe Acrobat，几秒钟即可在线完成。
两种 PDF 密码类型
PDF encryption supports two distinct passwords:
**Open password (user password):** Required to open and view the document. Anyone without this password sees only a password prompt.
**Owner password (permissions password):** Controls what an authorised viewer can do with the document — print it, copy text from it, edit it, or add annotations. The owner password is not required to open the file; it only restricts actions after opening.
You can set either or both. For simple confidentiality (preventing unauthorised viewing), set only an open password.
如何在线为 PDF 加密（分步指南）
1. Go to the WhiskFile Protect PDF tool.
2. Upload your PDF.
3. Enter an open password in the password field. This is the password recipients will need to open the file.
4. Optionally, configure permissions: allow or restrict printing, copying text, and editing.
5. Click "Protect PDF".
6. Download the encrypted PDF. Test it by opening it in a PDF viewer — you should be prompted for the password.
如何选择强 PDF 密码
PDF encryption strength depends on both the encryption level and the password strength. WhiskFile uses AES-256 encryption (the strongest available for PDFs).
Use a password of at least 12 characters with a mix of uppercase, lowercase, numbers, and symbols. Avoid dictionary words, names, or dates.
Important: PDF passwords cannot be recovered if lost. If you forget the password, the only way to access the document is with the original unencrypted version. Always store PDF passwords in a password manager.
如何安全分享加密的 PDF
Never send the password in the same message or email as the protected PDF. Instead:
1. Send the protected PDF by email. 2. Share the password via a different channel — text message, phone call, or a separate encrypted message.
This way, if the email is intercepted, the PDF cannot be opened without the separately shared password.
如何移除 PDF 密码
If you know the current password and want to remove it (to create an unprotected version), use the WhiskFile Unlock PDF tool. Enter the existing password, and the tool will produce an unencrypted PDF.
Note: the Unlock PDF tool only works if you know the password. It cannot remove passwords from files where the password is unknown.
常见问题
- WhiskFile 对 PDF 密码使用什么加密方式？
- WhiskFile 采用 AES-256 加密，这是 PDF 文件可用的最高加密级别，与 Adobe Acrobat 使用的标准相同。
- 不使用 Adobe Acrobat 可以给 PDF 加密吗？
- 可以。WhiskFile 的 PDF 加密工具可以直接在浏览器中为任何 PDF 添加 AES-256 加密，无需任何 Adobe 软件。
- PDF 密码足以保护敏感信息吗？
- 对于大多数情况，是的。对于强密码来说，通过暴力破解 AES-256 加密在计算上是不切实际的。但弱密码（短词、常见短语）容易被破解。对于高度敏感的信息，请使用强密码并结合加密存储等额外的安全措施。
- 我可以限制打印但允许查看吗？
- 可以。PDF 加密工具具备权限控制功能，你可以允许查看而不允许打印、复制或编辑——所有这些都可以独立配置。