How to Digitally Sign an Excel Document using Java

This crisp article has all the information on how to digitally sign an Excel document using Java. It contains the logical steps required for performing this task programmatically along with the runnable sample code to insert electronic signature in Excel using Java. You will also learn customization of this process to use a PFX for creating a digital signature and then putting this signature to the Excel file before saving it as an XLSX file or in any other supported format.

Steps to Create a Digital Signature in Excel using Java

  1. Configure the environment to use Aspose.Cells from the repository to sign the Excel file
  2. Instantiate a Keystore and load the certificate using the certificate file name and password
  3. Create a digital signature using the above keystore and the private key password
  4. Provide comments, signing date, and time for the digital signature
  5. Create a digital signature collection and add the newly created digital signature to it
  6. Load the workbook and add the digital signature collection to it
  7. Save the digitally signed workbook

These steps describe the procedure how to create an electronic signature in Excel using Java. A step-wise process is presented where first a keystore is created by using the PFX certificate and the private key password, then a digital signature collection is created and a new digital signature created with the help of the keystore is added to this collection. In the final step, the target workbook is loaded and the digital signature collection is added to it.

Code to Put Digital Signature in Excel using Java

In this code to digitally sign Excel using Java, a Keystore is created by using the cryptography PKCS12 and then the certificate file is loaded into it. The DigitalSignature is created by providing the Keystore, private key password, comments and user-provided signature time however you can also add signature image, provider id, and XAdESType. The output workbook can be saved in any of the supported formats like XLSX, XLS, XLSM, ODS, XLSB, etc.

This tutorial shared the process for digitally signing the Excel file however if you want to learn the process to convert Excel to an image, refer to the article on how to convert Excel sheets to Image in Java.