保护PDF

新

Password-protect your PDF

PDF工具

如何使用 保护PDF

  1. 1上传PDF
  2. 2输入密码并确认
  3. 3点击保护PDF
  4. 4下载受密码保护的文件

关于 保护PDF

保护PDF使用pdf-lib对文档进行密码加密。接收者需要密码才能打开文件。没有任何文件被上传——所有操作都在您的浏览器中完成。

保护PDF的主要功能

  • 快速准确的Protect Pdf处理
  • 无需安装——在浏览器中工作
  • 免费无限制
  • 隐私保护——数据永不离开浏览器
  • 移动和桌面兼容
  • 即时结果带实时预览
  • No watermarks or content changes applied
  • No account or installation required

支持的格式

输入格式

PDF (unprotected)

输出格式

PDF (RC4 128-bit password-protected)

Only user (open) password protection is applied. The PDF must not already be encrypted — unlock it first if needed.

示例

Protect a contract before emailing

Add a password to a PDF contract so only the intended recipient can open it.

输入

Unprotected contract PDF

输出

Password-protected PDF — recipients need the password to open

Secure a financial report

Encrypt a sensitive financial PDF before uploading to a shared drive.

输入

Financial report PDF

输出

Encrypted PDF with password access control

常见使用场景

  • 专业Protect Pdf任务
  • 快速日常计算
  • 教育目的和学习
  • 商业和工作场所生产力
  • 个人项目和爱好
  • Securing academic thesis drafts during external review

故障排除

意外结果

解决方案

检查输入格式并确保所有必填字段正确填写。

工具不工作

解决方案

清除浏览器缓存并刷新。确保启用 JavaScript。

Trying to protect a PDF that is already password-protected

解决方案

Unlock the PDF first with the Unlock PDF tool to remove the existing password, then add the new one.

常见问题

加密是在服务器上完成的吗？

不是。pdf-lib完全在您的浏览器中加密您的文件。

如果我忘记密码怎么办？

没有找回方式。请妥善保管您的密码。

What encryption algorithm is used?

pdf-lib applies RC4 128-bit encryption, which is the standard user-password protection scheme supported by Adobe Acrobat, macOS Preview, and all major PDF viewers.

Can I restrict printing or copying while still allowing opening?

Currently only user (open) password protection is supported. Owner permission restrictions — such as disabling printing or text copying — are not separately configurable in this tool.

Will password protection work in all PDF readers?

Yes. Standard PDF user password encryption is a core part of the PDF specification and is supported by Adobe Acrobat, macOS Preview, browser PDF viewers, mobile apps, and all major PDF software.

Can I protect a PDF that already has a password?

No. The tool requires an unprotected PDF as input. Use the Unlock PDF tool to remove the existing password first, then apply the new password.

Can the password contain spaces or special characters?

Yes. Any printable character is allowed including spaces, punctuation, and symbols. Avoid extremely unusual Unicode characters for maximum compatibility across PDF readers.

What is the maximum password length?

Standard PDF encryption supports passwords up to 32 characters. For strong security, use at least 12 characters combining uppercase letters, lowercase letters, numbers, and symbols.