Extract certificate from PDF on docker

Aspose.PDF Product Family
,
1

Hello,

I am trying to extract a user certificate from a signed pdf.

Everything is fine when I do it in windows but when I do it in docker the certificate that is extracted from the user signature is not the user certificate but the root certificate.

I am using Aspose.PDF 25.04.0 with .net9.

2

@rubecarreterowk

To extract a user certificate from a signed PDF in a Docker environment using Aspose.PDF, you can follow a similar approach as you would in a Windows environment. However, there are a few considerations to ensure that the correct certificate is extracted.

Here’s a sample code snippet that demonstrates how to extract the certificate from a signature field in a PDF document:

using System.IO;
using Aspose.Pdf.Forms;
using Aspose.Pdf;

namespace ExtractCertificateExample
{
    public class Program
    {
        public static void Main()
        {
            try
            {
                // Specify the path to your PDF document
                string inputFilePath = "path/to/your/signedDocument.pdf";
                
                using (Document pdfDocument = new Document(inputFilePath))
                {
                    foreach (Field field in pdfDocument.Form)
                    {
                        SignatureField signatureField = field as SignatureField;
                        if (signatureField != null)
                        {
                            Stream certificateStream = signatureField.ExtractCertificate();
                            if (certificateStream != null)
                            {
                                using (certificateStream)
                                {
                                    byte[] certificateBytes = new byte[certificateStream.Length];
                                    using (FileStream fs = new FileStream("output.cer", FileMode.CreateNew))
                                    {
                                        certificateStream.Read(certificateBytes, 0, certificateBytes.Length);
                                        fs.Write(certificateBytes, 0, certificateBytes.Length);
                                    }
                                }
                            }
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error: {ex.Message}");
            }
        }
    }
}

Troubleshooting Tips:

  1. Environment Differences: Ensure that the Docker environment has all necessary dependencies and configurations that might differ from your Windows setup. Sometimes, missing libraries or different versions can lead to unexpected behavior.

  2. File Permissions: Check the file permissions in your Docker container. Ensure that the application has the necessary permissions to read the PDF file and write the output certificate file.

  3. Aspose.PDF Version: Make sure you are using the same version of Aspose.PDF in Docker as you are in your Windows environment. Version discrepancies can lead to different behaviors.

  4. Debugging: Add logging to see what certificates are being extracted. This can help you determine if the issue is with the extraction process or with the PDF itself.

If you continue to experience issues, consider checking the Aspose forums for similar cases or posting your specific problem for further assistance.

3

The method signatureField.ExtractCertificate(); has a diferent behavior on docker and windows

4

@rubecarreterowk

Have you tried with Aspose.Pdf.Drawing for .NET instead of Aspose.PDF for .NET? Please share your sample PDF along with sample code snippet with us. Also, please share your docker file so that we can test the scenario in our environment and address it accordingly.