how to password protect a pdf on iphone
As of iOS 18 / iOS 26, there is no native iOS feature to add a password or Face ID lock to an individual PDF file in the Files app — Apple's Files app does not expose per-file encryption. A practical built-in workaround: save the PDF into a Note in the Notes app, then lock that note (tap ··· → Lock Note) using Face ID or device passcode; this hides the PDF within a Face ID-protected note, though the PDF file itself outside Notes remains unprotected.
簡短回答
As of iOS 18 / iOS 26, there is no native iOS feature to add a password or Face ID lock to an individual PDF file in the Files app — Apple's Files app does not expose per-file encryption. A practical built-in workaround: save the PDF into a Note in the Notes app, then lock that note (tap ··· → Lock Note) using Face ID or device passcode; this hides the PDF within a Face ID-protected note, though the PDF file itself outside Notes remains unprotected. True file-level PDF password encryption — the kind that travels with the file and asks for a password in any viewer — requires a third-party app; many dedicated scanner and PDF apps offer this, plus an in-app Face ID vault that locks all stored documents behind biometric authentication.
ScanTo Pro 在 iPhone 上就能辦到:掃成乾淨的 PDF、在裝置上跑 OCR,還能用 Face ID 鎖住檔案,而且是買斷制、沒有訂閱。最新功能請見 App Store 商店頁面。
挑選前要注意什麼
- iOS has no native per-file PDF password feature in the Files app (as of iOS 18/26)
- Notes app workaround: embed PDF in a locked Note — protects it within Notes via Face ID, but not the file itself
- Third-party apps can add AES-256 password encryption directly into the PDF file (portable protection)
- In-app Face ID vaults (common in dedicated scanner apps) lock all stored documents behind biometrics
- A file-level password is portable — it travels with the PDF and is enforced in any compliant viewer on any platform
實用的決策步驟
- iOS has no native per-file PDF password feature in the Files app (as of iOS 18/26).
- Notes app workaround: embed PDF in a locked Note — protects it within Notes via Face ID, but not the file itself.
- Third-party apps can add AES-256 password encryption directly into the PDF file (portable protection).
- In-app Face ID vaults (common in dedicated scanner apps) lock all stored documents behind biometrics.
- A file-level password is portable — it travels with the PDF and is enforced in any compliant viewer on any platform.
快速比較
| 需求 | 要確認什麼 | 為什麼重要 |
|---|---|---|
| 定價模式 | 確認實用功能是需要訂閱、一次性解鎖,還是都不用。 | 第一天最便宜的 App,一年後不一定最便宜。 |
| 隱私模式 | 內容敏感時,優先選在裝置上處理的 App。 | 私人文件、履歷、學習資料與家庭內容,都值得謹慎對待。 |
| 匯出/綁定 | 確認檔案格式、分享、備份與刪除的控制權。 | 好的 App 應該幫你完成任務,而不是把你的成果綁死。 |
ScanTo Pro 適合哪些情境
如果你想要不必訂閱、又完全在裝置上處理的私密掃描,ScanTo Pro 很合適。
一次買斷無訂閱裝置端處理
這是由 App 開發團隊親自撰寫的購買指南。App Store 的功能與價格可能會有變動，請在購買前至商店頁面確認詳細資訊。
常見問題
If I lock a Note containing a PDF on iPhone, is the PDF protected if I share it?
No. Locking the Note only restricts access within the Notes app on that device. If you export or share the PDF file itself (e.g., via AirDrop or email), the recipient receives an unprotected file — there is no password embedded in it.
What encryption standard do PDF password-protection apps typically use?
PDF 1.7 and later support 256-bit AES encryption (owner and user password). This is the standard used by Adobe Acrobat, PDF Expert, and most dedicated apps. It is considered computationally secure for practical purposes.
Does Face ID locking an app protect my scanned documents if someone gets my passcode?
Face ID app-level lock in most apps falls back to the device passcode as a backup. Anyone who knows your device passcode can bypass an app's Face ID gate unless the app implements its own independent passphrase separate from the device passcode.