How to Implement Custom QR-Code Serialization and Encryption in PDFs Using GroupDocs.Signature for Java

Introduction

In the digital age, secure document signing is essential for maintaining data integrity and authenticity. Enter GroupDocs.Signature for Java—a powerful library designed to simplify adding signatures to documents. This tutorial will guide you through implementing custom QR-code serialization with encryption in PDFs using GroupDocs.Signature for Java.

What You’ll Learn:

  • How to set up and configure GroupDocs.Signature for Java
  • Implementing custom serialization for QR-code signatures
  • Encrypting serialized data within a QR code
  • Applying these features to secure your documents

Before we dive into the implementation, let’s ensure you have everything needed to follow along.

Prerequisites

To effectively use this tutorial, make sure you meet the following prerequisites:

  1. Required Libraries and Dependencies:

    • GroupDocs.Signature for Java version 23.12 or higher
    • Maven or Gradle for dependency management (optional)

  2. Environment Setup Requirements:

    • Java Development Kit (JDK) installed on your machine
    • A basic understanding of Java programming

  3. Knowledge Prerequisites:

    • Familiarity with Java and object-oriented programming concepts
    • Basic knowledge of working with PDFs in Java

Setting Up GroupDocs.Signature for Java

To get started, you need to set up the GroupDocs.Signature library in your project environment.

Maven Installation

If you’re using Maven, add the following dependency to your pom.xml file:

<dependency>
    <groupId>com.groupdocs</groupId>
    <artifactId>groupdocs-signature</artifactId>
    <version>23.12</version>
</dependency>

Gradle Installation

For Gradle users, include this line in your build.gradle file:

implementation 'com.groupdocs:groupdocs-signature:23.12'

Direct Download

Alternatively, you can download the latest version directly from GroupDocs.Signature for Java releases.

License Acquisition Steps

  • Free Trial: Start by downloading a trial version to test out its features.
  • Temporary License: You can request a temporary license if needed, which allows you to evaluate the product without any restrictions.
  • Purchase: For long-term use, consider purchasing a full license.

Once installed, initialize GroupDocs.Signature in your project:

import com.groupdocs.signature.Signature;

public class SetupGroupDocs {
    public static void main(String[] args) {
        Signature signature = new Signature("YOUR_DOCUMENT_DIRECTORY/sample.pdf");
        // Your code here...
    }
}

Implementation Guide

Now, let’s dive into implementing custom QR-code serialization and encryption with GroupDocs.Signature for Java.

Custom Serialization Class for QR-Code Signatures

Overview

This feature involves creating a class that handles the serialization of metadata into a QR-code signature. The DocumentSignatureData class stores attributes such as ID, author, signed date, and data factor.

import com.groupdocs.signature.domain.extensions.serialization.FormatAttribute;
import java.math.BigDecimal;
import java.util.Date;

class DocumentSignatureData {
    @FormatAttribute(propertyName = "SignID")
    public String ID;

    public void setID(String value) { 
        this.ID = value; 
    }

    @FormatAttribute(propertyName = "SAuth")
    public String author;

    public void setAuthor(String value) {
        this.author = value;
    }

    @FormatAttribute(propertyName = "SDate", propertyFormat = "yyyy-MM-dd")
    public Date signed = new Date();

    public void setSigned(Date value) {
        this.signed = value;
    }

    @FormatAttribute(propertyName = "SDFact", propertyFormat = "N2")
    public BigDecimal dataFactor = new BigDecimal(0.01);

    public void setDataFactor(BigDecimal value) {
        this.dataFactor = value;
    }
}

Explanation

  • Attributes: The @FormatAttribute annotations specify how each attribute is serialized into the QR code.
    • ID: A unique identifier for the signature.
    • Author: The person who signed the document.
    • Signed Date: Timestamp of when the document was signed.
    • Data Factor: Additional numerical data associated with the signature.

QR-Code Signature with Custom Data Serialization and Encryption

Overview

This section demonstrates how to sign a document using a QR-code that includes custom serialized data and encryption.

import com.groupdocs.signature.Signature;
import com.groupdocs.signature.domain.Padding;
import com.groupdocs.signature.domain.enums.HorizontalAlignment;
import com.groupdocs.signature.domain.enums.VerticalAlignment;
import com.groupdocs.signature.domain.extensions.encryption.IDataEncryption;
import com.groupdocs.signature.domain.qrcodes.QrCodeTypes;
import com.groupdocs.signature.exception.GroupDocsSignatureException;
import com.groupdocs.signature.options.sign.QrCodeSignOptions;
import java.io.File;
import java.math.BigDecimal;
import java.util.Date;
import java.util.UUID;

class SignWithQRCodeCustomSerialization {
    String filePath = "YOUR_DOCUMENT_DIRECTORY/sample.pdf"; 
    String outputFilePath = new File("YOUR_OUTPUT_DIRECTORY", "SignedQRCodeCustomSerialization.pdf").getPath();

    public void signDocument() throws Exception {
        Signature signature = new Signature(filePath);

        // Implement your custom encryption logic here
        IDataEncryption encryption = new CustomXOREncryption();

        DocumentSignatureData documentSignature = new DocumentSignatureData();
        documentSignature.setID(UUID.randomUUID().toString());
        documentSignature.setAuthor(System.getenv("USERNAME")); 
        documentSignature.setSigned(new Date());
        documentSignature.setDataFactor(new BigDecimal("11.22"));

        QrCodeSignOptions options = new QrCodeSignOptions();
        options.setData(documentSignature);
        options.setEncodeType(QrCodeTypes.QR);
        options.setDataEncryption(encryption);

        // Configure alignment and appearance
        options.setHeight(100);
        options.setWidth(100);
        options.setVerticalAlignment(VerticalAlignment.Bottom);
        options.setHorizontalAlignment(HorizontalAlignment.Right);
        
        Padding padding = new Padding();
        padding.setRight(10);
        padding.setBottom(10);
        options.setMargin(padding);

        signature.sign(outputFilePath, options);
    }
}

Explanation

  • Custom Encryption: Implement your own encryption logic in CustomXOREncryption or use any other method implementing IDataEncryption.
  • Signature Options: Configure the QR-code’s appearance and alignment with options like height, width, padding, etc.
  • Signing Process: The signature.sign() method applies the QR-code signature to the document.

Troubleshooting Tips

  • Ensure all dependencies are correctly configured in your build tool (Maven/Gradle).
  • Verify that the file paths for input and output documents are accurate.
  • Confirm that your custom encryption logic is properly implemented and integrated.

Practical Applications

Here are some real-world applications of this feature:

  1. Legal Document Signing: Securely sign contracts with metadata embedded in QR codes to ensure authenticity.
  2. Invoice Processing: Automatically add encrypted signatures to invoices for added security and traceability.
  3. Logistics Tracking: Use signed documents for shipment tracking, embedding unique identifiers and timestamps within QR codes.
  4. Academic Certifications: Embed student information securely into digital certificates using QR-code signature