Troubleshooting "Convert: Not Authorized" Error When Converting JPG to PDF in Ubuntu

Encountering errors while trying to convert JPG files to PDF using the convert command in Ubuntu can be frustrating. One common error message is: "convert: not authorized `pictures.pdf' @ error/constitute.c/WriteImage/1028." This article will explore the root cause of this error and provide several solutions to get you back on track with your image conversions.

Understanding the "Not Authorized" Error

The "not authorized" error typically arises due to a security update in ImageMagick, a software suite used by the convert command. This update restricts the ability to convert certain file types, including PDF, as a security measure to prevent potential vulnerabilities. Specifically, the policy.xml file, which controls ImageMagick's behavior, is configured to deny write access to PDF files by default.

Solutions to Resolve the Error

Here are several methods to resolve the "convert: not authorized" error, ranging from temporary workarounds to more permanent solutions:

1. Modifying the policy.xml File (Temporary Fix)

This approach involves directly editing the policy.xml file to grant ImageMagick the necessary permissions to write PDF files.

Steps:

1. Open the policy.xml file with root privileges using a text editor. The file is typically located at /etc/ImageMagick-6/policy.xml.

   sudo nano /etc/ImageMagick-6/policy.xml
   

2. Locate the section that restricts PDF rights. It usually looks like this:

   <policy domain="coder" rights="none" pattern="PDF" />
   

3. Change the rights attribute from "none" to "read|write":

   <policy domain="coder" rights="read|write" pattern="PDF" />
   

   Alternatively, you can comment out the entire line by enclosing it in <!-- and -->:

   <!-- <policy domain="coder" rights="none" pattern="PDF" /> -->
   

4. Save the changes and exit the text editor.

Important Considerations:

• Security Implications: Modifying security settings can expose your system to potential risks. Be aware of the implications before making changes. Refer to resources like kb.cert.org/vuls/id/332928 for more information on the security context.
• Temporary Nature: This fix might be overwritten by future updates to ImageMagick.

2. Using a sed One-Liner (Automated Modification)

For a quicker, programmatic approach, you can use the sed command to modify the policy.xml file:

sudo sed -i 's#<policy domain="coder" rights="none" pattern="PDF" />#<policy domain="coder" rights="read|write" pattern="PDF" />#' /etc/ImageMagick-6/policy.xml

This command automatically replaces the "none" rights with "read|write" for PDF files in the policy.xml file.

3. Using img2pdf (Recommended Secure Alternative)

A more secure and recommended solution is to use the img2pdf tool, which is specifically designed for converting images to PDF without relying on potentially insecure ImageMagick configurations.

Installation:

sudo apt-get install img2pdf

Usage:

img2pdf --output out.pdf in.jpg

img2pdf offers a safer alternative because it avoids the security limitations imposed on ImageMagick. It is often the best choice for users concerned about system security.

4. Using pdftoppm (Alternative Approach)

Another alternative involves using pdftoppm from the poppler-utils package to convert the PDF to a series of JPG images, if the goal is to convert from PDF to JPG.

Installation:

sudo apt-get install poppler-utils

Usage:

pdftoppm -jpeg input.pdf output.jpg

This will convert each page of the PDF to a separate JPG file.

Choosing the Right Solution

The best approach depends on your specific needs and security considerations:

• Quick Fix (Temporary): Modifying the policy.xml file can be a quick way to resolve the error, but it's crucial to understand the security implications.
• Secure and Recommended: Using img2pdf provides a secure alternative for converting images to PDF.
• PDF to JPG Conversion: If your goal is to convert from PDF to JPG, pdftoppm offers a viable solution.

By understanding the cause of the "convert: not authorized" error and exploring these solutions, you can effectively troubleshoot the issue and continue converting your JPG files to PDF in Ubuntu. Remember to prioritize security and choose the method that best suits your requirements.