Sample code in C# for pattern redaction and highlighting

This guide provides C# code examples for implementing document security features using Nutrient Document Converter Services (DCS). Document security is essential for protecting sensitive information in various scenarios:

  • Pattern redaction - Permanently removes sensitive content like social security numbers, credit card numbers, or personal identifiable information
  • Pattern highlighting - Visually marks sensitive content without removing it, useful for review processes
  • Smart redaction - Uses intelligent algorithms to automatically identify and redact common sensitive data patterns

Choose the appropriate method based on your security requirements and compliance needs.

Prerequisites

Before implementing document security features, ensure you have:

  • Nutrient Document Converter Services installed and running
  • .NET Framework or .NET Core development environment
  • Document files for testing security operations
  • Implemented OpenService and CloseService methods from the DocumentConverterServiceClient sample code
  • Appropriate permissions for file system access

Pattern redaction sample code 

        /// <summary>
        /// Perform Smart Redaction on the supplied file, writing the result into the target folder
        /// </summary>
        /// <param name="ServiceURL">URL endpoint for the PDF Converter service</param>
        /// <param name="sourceFileName">Source filename</param>
        /// <param name="targetFolder">Target folder to receive the output file</param>
        static void SmartRedaction(string ServiceURL, string sourceFileName, string targetFolder)
        {
            DocumentConverterServiceClient client = null;
            try
            {
                // Create minimum OpenOptions object
                OpenOptions openOptions = new OpenOptions();
                openOptions.OriginalFileName = Path.GetFileName(sourceFileName);


                // Create minimum SmartRedactionSettings
                SmartRedactionSettings smartRedactionSettings = new SmartRedactionSettings();
                smartRedactionSettings = new SmartRedactionSettings();
                // Set what needs to be redacted
                smartRedactionSettings.RedactCreditCardNumbers = BooleanEnum.True;
                smartRedactionSettings.RedactEmailAddresses = BooleanEnum.True;
                smartRedactionSettings.RedactPhoneNumbers = BooleanEnum.True;


                // Create target folder if required
                if (!Directory.Exists(targetFolder))
                {
                    Directory.CreateDirectory(targetFolder);
                }
                // ** Read the source file into a byte array.
                byte[] sourceFile = File.ReadAllBytes(sourceFileName);


                // ** Open the service and configure the bindings
                client = OpenService(ServiceURL);


                // ** Carry out the conversion.
                byte[] result = client.SmartRedaction(sourceFile, openOptions, smartRedactionSettings);


                // ** Save the results
                if (result != null)
                {
                    if (!Directory.Exists(targetFolder))
                    {
                        Directory.CreateDirectory(targetFolder);
                    }
                    string filename = Path.GetFileNameWithoutExtension(sourceFileName);
                    string destinationFileName = Path.GetFullPath(Path.Combine(targetFolder, filename + "-redacted.pdf"));
                    using (FileStream fs = File.Create(destinationFileName))
                    {
                        fs.Write(result, 0, result.Length);
                        fs.Close();
                    }
                    Console.WriteLine("File converted to " + destinationFileName);
                }


                else
                {
                    Console.WriteLine("Nothing returned");
                }
            }
            catch (FaultException<WebServiceFaultException> ex)
            {
                Console.WriteLine($"FaultException occurred: ExceptionType: {ex.Detail.ExceptionType.ToString()}");
                Console.WriteLine();
                Console.WriteLine($"Error Detail: {string.Join(Environment.NewLine, ex.Detail.ExceptionDetails)}");
                Console.WriteLine($"Error message: {ex.Message}");
                Console.WriteLine();
                Console.WriteLine($"Error reason: {ex.Reason}");
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                Console.WriteLine(ex.StackTrace);
                Console.WriteLine(ex.Data.ToString());
            }
            finally
            {
                if (client != null)
                {
                    CloseService(client);


                }
            }


        }

Pattern highlighting sample code

Pattern highlighting identifies specific patterns in a document and visually highlights them without removing the underlying content. This example shows how to implement pattern highlighting using the API:

        /// <summary>
        /// Perform pattern redaction on the supplied file, writing the result into the target folder.
        /// </summary>
        /// <param name="ServiceURL">URL endpoint for the PDF Converter service.</param>
        /// <param name="sourceFileName">Source filename.</param>
        /// <param name="targetFolder">Target folder to receive the output file.</param>
        static void PatternRedaction(string ServiceURL, string sourceFileName, string targetFolder)
        {
            DocumentConverterServiceClient client = null;
            try
            {
                // Create minimum `OpenOptions` object.
                OpenOptions openOptions = new OpenOptions();
                openOptions.OriginalFileName = Path.GetFileName(sourceFileName);


                // Create minimum `PatternHighlightSettings`.
                PatternHighlightSettings patternHighlightSettings = new PatternHighlightSettings();
                // Set the highlight color.
                patternHighlightSettings.Red = 0;
                patternHighlightSettings.Green = 0;
                patternHighlightSettings.Blue = 255;
                patternHighlightSettings.Alpha = 255;
                patternHighlightSettings.Pattern = "\"374245455400126\"";


                // Create target folder if required.
                if (!Directory.Exists(targetFolder))
                {
                    Directory.CreateDirectory(targetFolder);
                }
                // ** Read the source file into a byte array.
                byte[] sourceFile = File.ReadAllBytes(sourceFileName);


                // ** Open the service and configure the bindings.
                client = OpenService(ServiceURL);


                // ** Carry out the highlighting.
                byte[] result = client.PatternHighlight(sourceFile, openOptions, patternHighlightSettings);


                // ** Save the results.
                if (result != null)
                {
                    if (!Directory.Exists(targetFolder))
                    {
                        Directory.CreateDirectory(targetFolder);
                    }
                    string filename = Path.GetFileNameWithoutExtension(sourceFileName);
                    string destinationFileName = Path.GetFullPath(Path.Combine(targetFolder, filename + "-highlighted.pdf"));
                    using (FileStream fs = File.Create(destinationFileName))
                    {
                        fs.Write(result, 0, result.Length);
                        fs.Close();
                    }
                    Console.WriteLine("File converted to " + destinationFileName);
                    // Open the destination file.
                    ProcessStartInfo psi = new ProcessStartInfo();
                    psi.FileName = destinationFileName;
                    psi.UseShellExecute = true;
                    Process.Start(psi);
                }
                else
                {
                    Console.WriteLine("Nothing returned");
                }
            }
            catch (FaultException<WebServiceFaultException> ex)
            {
                Console.WriteLine($"FaultException occurred: ExceptionType: {ex.Detail.ExceptionType.ToString()}");
                Console.WriteLine();
                Console.WriteLine($"Error Detail: {string.Join(Environment.NewLine, ex.Detail.ExceptionDetails)}");
                Console.WriteLine($"Error message: {ex.Message}");
                Console.WriteLine();
                Console.WriteLine($"Error reason: {ex.Reason}");
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                Console.WriteLine(ex.StackTrace);
                Console.WriteLine(ex.Data.ToString());
            }
            finally
            {
                if (client != null)
                {
                    CloseService(client);


                }
            }


        }

Smart redaction sample code 

        /// <summary>
        /// Perform Smart Redaction on the supplied file, writing the result into the target folder
        /// </summary>
        /// <param name="ServiceURL">URL endpoint for the PDF Converter service</param>
        /// <param name="sourceFileName">Source filename</param>
        /// <param name="targetFolder">Target folder to receive the output file</param>
        static void SmartRedaction(string ServiceURL, string sourceFileName, string targetFolder)
        {
            DocumentConverterServiceClient client = null;
            try
            {
                // Create minimum OpenOptions object
                OpenOptions openOptions = new OpenOptions();
                openOptions.OriginalFileName = Path.GetFileName(sourceFileName);


                // Create minimum SmartRedactionSettings
                SmartRedactionSettings smartRedactionSettings = new SmartRedactionSettings();
                smartRedactionSettings = new SmartRedactionSettings();
                // Set what needs to be redacted
                smartRedactionSettings.RedactCreditCardNumbers = BooleanEnum.True;
                smartRedactionSettings.RedactEmailAddresses = BooleanEnum.True;
                smartRedactionSettings.RedactPhoneNumbers = BooleanEnum.True;


                // Create target folder if required
                if (!Directory.Exists(targetFolder))
                {
                    Directory.CreateDirectory(targetFolder);
                }
                // ** Read the source file into a byte array.
                byte[] sourceFile = File.ReadAllBytes(sourceFileName);


                // ** Open the service and configure the bindings
                client = OpenService(ServiceURL);


                // ** Carry out the conversion.
                byte[] result = client.SmartRedaction(sourceFile, openOptions, smartRedactionSettings);


                // ** Save the results
                if (result != null)
                {
                    if (!Directory.Exists(targetFolder))
                    {
                        Directory.CreateDirectory(targetFolder);
                    }
                    string filename = Path.GetFileNameWithoutExtension(sourceFileName);
                    string destinationFileName = Path.GetFullPath(Path.Combine(targetFolder, filename + "-redacted.pdf"));
                    using (FileStream fs = File.Create(destinationFileName))
                    {
                        fs.Write(result, 0, result.Length);
                        fs.Close();
                    }
                    Console.WriteLine("File converted to " + destinationFileName);
                }


                else
                {
                    Console.WriteLine("Nothing returned");
                }
            }
            catch (FaultException<WebServiceFaultException> ex)
            {
                Console.WriteLine($"FaultException occurred: ExceptionType: {ex.Detail.ExceptionType.ToString()}");
                Console.WriteLine();
                Console.WriteLine($"Error Detail: {string.Join(Environment.NewLine, ex.Detail.ExceptionDetails)}");
                Console.WriteLine($"Error message: {ex.Message}");
                Console.WriteLine();
                Console.WriteLine($"Error reason: {ex.Reason}");
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                Console.WriteLine(ex.StackTrace);
                Console.WriteLine(ex.Data.ToString());
            }
            finally
            {
                if (client != null)
                {
                    CloseService(client);


                }
            }


        }

Troubleshooting

Pattern matching error: Pattern not found

  • Verify that the pattern exists in the document
  • Check pattern syntax and escape special characters
  • Ensure the pattern format matches the document content structure

Security operation error: Permission denied

  • Verify that the application has read access to source documents
  • Check that the output directory has write permissions
  • Ensure documents aren’t password-protected or locked by other applications

Service connection error: Cannot connect to DCS

  • Ensure Nutrient Document Converter Services is running and accessible
  • Verify the service URL in your code matches your DCS installation
  • Check that no firewall is blocking the connection

Performance issues: Slow processing

  • Consider processing documents in batches for large volumes
  • Optimize pattern complexity to reduce processing time
  • Monitor memory usage for large documents

What’s next

Now that you understand document security implementation with C#, explore these related capabilities: