Add Security to PDF with PDF.co API Add Security to PDF Step 1: Upload PDF to Add Security Select the PDF file you want to secure. Upload PDF Step 2: Add Security to Uploaded PDF Once you have uploaded your PDF file, enter the security details and click the "Add Security" button. Owner Password: User Password (optional): Encryption Algorithm: AES_128bit AES_256bit RC4_40bit RC4_128bit Allow Print Document: Allow Fill Forms: Allow Modify Document: Allow Content Extraction: Allow Modify Annotations: Print Quality: High Resolution Low Resolution Add Security