Java: Add or Delete Digital Signatures in Excel

A digital signature is an electronic signature with encrypted information that helps verify the authenticity of messages, software and digital documents. They are commonly used in software distribution, financial transactions, contract management software, and other situations that require forgery or tampering detection. When generating an Excel report, you may need to add a digital signature to make it look more authentic and official. In this article, you will learn how to add or delete digital signatures in Excel in Java using Spire.XLS for Java.

• Add a Digital Signature to Excel
• Delete All Digital Signatures from Excel

Install Spire.XLS for Java

First of all, you're required to add the Spire.Xls.jar file as a dependency in your Java program. The JAR file can be downloaded from this link. If you use Maven, you can easily import the JAR file in your application by adding the following code to your project's pom.xml file.

<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <name>e-iceblue</name>
        <url>https://repo.e-iceblue.com/nexus/content/groups/public/</url>
    </repository>
</repositories>
<dependencies>
    <dependency>
        <groupId>e-iceblue</groupId>
        <artifactId>spire.xls</artifactId>
        <version>14.11.0</version>
    </dependency>
</dependencies>
    

Add a Digital Signature to Excel in Java

You can add a digital signature to protect the integrity of an Excel file. Once the digital signature is added, the file becomes read-only to discourage further editing. If someone makes changes to the file, the digital signature will become invalid immediately.

Spire.XLS for Java provides the addDigitalSignature method of Workbook class to add digital signatures to an Excel file. The detailed steps are as follows:

• Instantiate a Workbook instance.
• Load an Excel file using Workbook.loadFromFile() method.
• Instantiate a CertificateAndPrivateKey instance with the specified certificate (.pfx) file path and the password of the .pfx file.
• Add a digital signature to the file using Workbook.addDigitalSignature(CertificateAndPrivateKey, String, Date) method.
• Save the result file using Workbook.saveToFile() method.

import com.spire.xls.ExcelVersion;
import com.spire.xls.Workbook;
import com.spire.xls.digital.CertificateAndPrivateKey;

import java.util.Date;

public class AddDigitalSignature {
    public static void main(String []args) throws Exception {
        //Create a Workbook instance
        Workbook workbook=new Workbook();
        //Load an Excel file
        workbook.loadFromFile("Sample.xlsx");

        //Add a digital signature to the file
        CertificateAndPrivateKey cap = new CertificateAndPrivateKey("Test.pfx","e-iceblue");
        workbook.addDigitalSignature(cap, "e-iceblue",new Date());

        //Save the result file
        workbook.saveToFile("AddDigitalSignature.xlsx", ExcelVersion.Version2013);
    }
}

Delete Digital Signature from Excel in Java

Spire.XLS for Java provides the removeAllDigitalSignatures method of Workbook class for developers to remove digital signatures from an Excel file. The detailed steps are as follows:

• Initialize an instance of the Workbook class.
• Load an Excel file using Workbook.loadFromFile() method.
• Remove all digital signatures from the file using Workbook.removeAllDigitalSignatures() method.
• Save the result file using Workbook.saveToFile() method.

import com.spire.xls.ExcelVersion;
import com.spire.xls.Workbook;

public class DeleteDigitalSignature {
    public static void main(String []args) throws Exception {
        //Create a Workbook instance
        Workbook workbook = new Workbook();
        //Load an Excel file
        workbook.loadFromFile("AddDigitalSignature.xlsx");

        //Remove all digital signatures in the file
        workbook.removeAllDigitalSignatures();

        //Save the result file
        workbook.saveToFile("RemoveDigitalSignature.xlsx", ExcelVersion.Version2013);
    }
}

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