Free Online PDF Encryption

Using Micro PDF's PDF encryption tool, set two types of password protection for PDF files: "Open Password" (restrict unauthorized viewing) and "Edit Password" (restrict modification, copying, printing). Supports 128-bit AES encryption algorithm, encryption strength meets industry security standards. Suitable for protecting contracts, financial reports, confidential documents and other sensitive content, preventing information leakage or tampering.

Whether it's a single important document or batch confidential files, Micro PDF can encrypt quickly. Free users can enjoy basic encryption functions to meet daily information security needs.

Table of Contents

• Key Points
• How to Use Micro PDF for PDF Encryption
• Encryption Types and Permission Settings
• Encryption Strength and Security Information
• Multi-Platform Support and Batch Encryption Features
• Frequently Asked Questions

Key Points

• Dual password protection: Supports setting "Open Password" (must enter to view) and "Edit Password" (restrict operation permissions).
• Fine-grained permission control: Can separately restrict printing (allow/prohibit), copying text (allow/prohibit), editing content (allow/prohibit).
• High-strength encryption: Uses 128-bit AES encryption algorithm, meets international security standards, difficult to crack.
• Free basic functions: Single file up to 200MB encrypts free, supports setting open password, unlimited daily usage.
• Batch processing: Encrypt up to 5 files per session, encryption process doesn't change original PDF content and format.

How to Use Micro PDF for PDF Encryption

Micro PDF's PDF encryption tool is simple to operate, completed in 3 steps:

1. Visit Micro PDF official website: Micro PDF, click on the "PDF Encryption" tool entry.
2. Upload PDF files for encryption (supports drag-and-drop upload, maximum 5 files per session).
3. Configure encryption options:
   • Open password: Set 6-32 digit password (required, free users only support this option).
   • Edit password (VIP): Set independent password for managing permissions.
   • Permission settings (VIP): Check allow/prohibit printing, copying, editing operations.
4. Click "Start Encryption", click "Download Encrypted File" to save encrypted PDF after completion.

Encryption Strategies for Different Scenarios

• Highly confidential documents (such as contracts): Set open password + edit password, prohibit copying and editing, allow only low-resolution printing.
• Internal sharing documents: Set only edit password, allow viewing and printing, but prohibit modifying content (suitable for team collaboration).
• External presentation documents: Set open password, allow all operations (printing/copying/editing), only restrict unauthorized viewing.

Encryption Types and Permission Settings

Micro PDF provides flexible encryption options to meet different security needs:

Permission Details:

• Print permission: Can choose "Prohibit printing", "Low-resolution printing only" (prevent high-definition copying), "Allow printing".
• Copy permission: After prohibiting copying, users cannot select or copy text and images in PDF.
• Edit permission: After prohibiting editing, cannot modify text, images, or add/delete pages.

Encryption Strength and Security Information

Micro PDF adopts industry-leading encryption technology to ensure document security:

• Encryption algorithm: 128-bit AES encryption (Advanced Encryption Standard), widely adopted by global governments and enterprises, extremely difficult to crack.
• Password requirements: Supports letter (uppercase/lowercase), number, special symbol combinations, recommend length ≥8 digits to enhance security.
• No backdoor design: Encryption process completed on user device (web version is temporary processing), Micro PDF cannot access or reset passwords, ensuring only users control access permissions.
• Compatibility: Encrypted PDF can be opened normally in all mainstream readers (Adobe Acrobat, Foxit, browser built-in readers) after entering correct password.

Multi-Platform Support and Batch Encryption Features

Micro PDF's PDF encryption tool supports all-scenario usage:

• Web-based: Computer browser batch encrypts files, suitable for office scenarios processing contracts, reports and other sensitive documents.
• Mobile: WeChat mini-program "Micro PDF" supports phone upload of PDF encryption, suitable for emergency document protection while traveling.
• Desktop: Client supports offline encryption of unlimited size PDF, batch processing 50+ files, encryption speed improved by 40%.

Frequently Asked Questions

1. If I forget the encryption password, can Micro PDF help decrypt?

No. The encryption process uses no backdoor design, Micro PDF cannot access or reset passwords, please keep passwords properly.

2. What's the difference between free user and VIP user encryption functions?

3. Can encrypted PDF have encryption removed?

Yes. Use Micro PDF's "PDF Decrypt" tool, enter the correct encryption password to remove password protection (requires original password).

4. Does encryption change PDF content or format?

No. Encryption only adds password protection, doesn't modify any content in PDF such as text, images, layout, identical to original file after decryption.

5. Can multiple PDFs be set with the same password?

Yes. During batch encryption, all files will apply the same password settings, suitable for unified management (such as batch encrypting the same batch of confidential documents).

6. Can encrypted PDF be opened on mobile phones?

Yes. All mainstream mobile PDF readers (such as Adobe Acrobat Reader, WeChat built-in reader) support entering password to open encrypted PDF.

7. How to confirm PDF has been successfully encrypted?

After encryption completion, open file with reader, if prompted "Password required to open" or "Permissions restricted", encryption is successful; can also upload encrypted file in Micro PDF, tool will display "Encrypted" status.