This article explains what a digital signature is, what it can be used for, and how you can use digital signatures in Microsoft Office Word 2007, Microsoft Office Excel 2007 and Microsoft Office PowerPoint 2007. For any question, please contact javacardos@gmail.com .

You can digitally sign a document for many of the same reasons you might sign a paper document. A digital signature is used to authenticate (authenticate: The process of verifying that people and products are who and what they claim to be. For example, confirming the source and integrity of a software publisher's code by verifying the digital signature used to sign the code.) digital information — such as documents, e-mail messages, and macros — by using computer cryptography. Digital signatures help to establish the following assurances:

Authenticity:The digital signature helps to assure that the signer is who he or she claims to be.

Integrity: The digital signature helps to assure that the content has not been changed or tampered with since it was digitally signed.

Non-repudiation: The digital signature helps to prove to all parties the origin of the signed content. “Repudiation” refers to the act of a signer's denying any association with the signed content.

1. eJavaToken(Make sure that PKI applet has been already upload).

2. PC with Windows server 2008 (used to set up certificate server).

• Insert eJavaToken into computer (Make sure that PKI applet has been already in eJavaToken).

• Open Internet Explorer, enter the url set in previous step, which is used to issue smart card certificate, press Enter.

• On Advanced Certificate Request page, select “Smartcard User” for Certificate Template option,select “EnterSafe ePass2003 CSP v1.0” for CSP option, then click Submit.

• Follow the prompts, select “Install this certificate” and click “Ok” until the certificate is installed successfully.

• If “This CA is not trusted” appears, please follow the prompts to add this CA into trust list.

After certificate is downloaded and installed successfully, you can view this certificate or apply for a new one. You can also click here to know more about download certificate. Note: Before download certificate, you need to configure the certificate server, you can refer to Set up smart card certificate management environmentand Issue smart card certificate management .

The followings show how to sign office document with eJavaToken. Take Microsoft Office Professional Plus 2007 - Office Word as an example. This section applies to the following 2007 Microsoft Office system programs: Excel, Word and PowerPoint.

• Firstly, make sure that eJava Token with certificate inside has been already inserted into computer.

• Open a word document in Microsoft Office Word 2007, click the Microsoft Office Button, point to Prepare, and then click Add a Digital Signature, as the figure shows below:

Microsoft Office 2010 and later version, adding digital signatures and encrypting documents need to click “File - >Info - >protect Document” and select the corresponding operation from submenu, as the below figure shows.

• A prompt window “Microsoft Office Word” will pop up, click “OK”, then “Signature Confirmation” will appear.

• In “Sign” dialog box, click “Change” button, select the certificate saved in eJavaToken and click “OK”. For example, select test1 certificate issued by ECCA, click “Sign”.

• Enter the correct PIN code. Now, the document signature has been completed.

• After your signature has been successfully saved with this document, there will be a red signature icon appearing on the state bar.When you points to this icon, it will show that “This document contains signatures”.

• Click signature icon on the state bar, the below dialog box will pop up.Right-click the certificate name, select “Signature Details…”from the menu to check the certificate detailed content.

You can also click the Microsoft Office Button, and then click Prepare - >View Signatures to open Signature dialog box.

• After a document has been digitally signed, it becomes read-only to prevent modifications.So, anyone can not edit or modify this document now.

If you want to modify the document, remove the current digital signature. Right-click the signature certificate name, select “Remove Signature” from the menu. Then click Yes to remove this signature.

• After removing signature, the signature icon will disappear as well.

And it cannot use digital signature to prove that this document is real and effective anymore.If you want to make this document real and effective, you should re-sign this document again.

Note: When you review any signed content, you should look at the attached signature details and the certificate used to create that signature to find out whether there are any potential problems.

Microsoft Office 2010 and later version, after your signature has been successfully saved with this document, at the top of document, you can also see a message bar of“Marked as Final” .

The following image shows the Message Bar alerting you to a signed document in read-only mode. You can click “Edit Anyway” to remove the current digital signature and edit this document.

In Office 2007 and later, Microsoft Corporation offers a built-in encryption tool - convenient, free installation and secure. Take Office Word 2007 as an example to introduce the operation steps:

• Click the Office button, hover the mouse pointer over “Prepare” and then click “Encrypt Document”.

• You will be asked to enter a password in the pop-up window, then click “OK”. You don’t need any other tools.

Note: This password is needed every time you open the encrypted document.

If you want to cancel the set password, just delete the password (so that there is no password)in “Encrypt Document” dialog box and click “OK”.