Fix: Add PyCryptodome dependency for encrypted PDF processing

[danielaskdd]

Fix: Add PyCryptodome dependency for encrypted PDF processing

Problem

When processing encrypted PDF files, the system would fail with the error:

"error_type": "file_extraction_error"
Failed to extract text from PDF: PyCryptodome is required for AES algorithm

This occurred because PyPDF2 requires the pycryptodome package to decrypt and extract text from password-protected or AES-encrypted PDF files, but this dependency was not installed.

• Related Issue: Fixed [Bug]:PyCryptodome is required for AES algorithm #2288

Solution

Added pycryptodome>=3.0.0,<4.0.0 as a dependency across all installation methods to ensure encrypted PDFs can be processed successfully.

Changes

1. pyproject.toml

• Added pycryptodome>=3.0.0,<4.0.0 to the offline-docs optional dependencies
• Maintains alphabetical ordering within the dependency list
• Ensures pip install lightrag-hku[offline-docs] includes pycryptodome

2. requirements-offline-docs.txt

• Added pycryptodome>=3.0.0,<4.0.0 to document processing dependencies
• Ensures offline document processing installations include the package

3. requirements-offline.txt

• Added pycryptodome>=3.0.0,<4.0.0 to complete offline dependencies
• Maintains consistency across all offline installation methods

4. lightrag/api/routers/document_routes.py

• Added runtime check and auto-installation for pycryptodome (line 1086-1087)
• Automatically installs pycryptodome if missing during PDF processing
• Mirrors the existing pattern for pypdf2 installation

5. uv.lock

• Automatically updated by package manager to include pycryptodome and all its platform-specific wheels

Benefits

• ✅ Supports both regular and encrypted PDF files
• ✅ Eliminates "PyCryptodome is required for AES algorithm" error
• ✅ Automatic installation fallback if dependency is missing
• ✅ Consistent across all installation methods (pip, offline, requirements files)

Testing

To verify the fix works:

1. Install the updated dependencies
2. Upload an encrypted PDF file through the API
3. Verify successful text extraction without errors