This article explains why you need a digital signature (or digital ID) to digitally sign a Microsoft Office document and how you can get one.
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What is a digital signature?
A digital signature or ID is more commonly known as a digital certificate (certificate: A digital means of proving identity and authenticity. Certificates are issued by a certification authority, and like a driver's license, can expire or be revoked.). To digitally sign an Office document, you must have a current (not expired) digital certificate. Digital certificates are typically issued by a certificate authority (CA) (certificate authority (CA): A commercial organization that issues digital certificates, keeps track of who is assigned to a certificate, signs certificates to verify their validity, and tracks which certificates are revoked or expired.), which is a trusted (trust: Indicates whether you trust the individual or group to whom the certificate is issued. The default setting is Inherit Trust from Issuer, which means that the certificate is trusted because the issuer, usually a certificate authority, is trusted.) third-party entity that issues digital certificates for use by other parties. There are many commercial third-party certificate authorities from which you can either purchase a digital certificate or obtain a free digital certificate. Many institutions, governments, and corporations can also issue their own certificates.
A digital certificate is necessary for a digital signature because it provides the public key (public key: The nonsecret half of a cryptographic key pair that is used with a public key algorithm. Public keys are typically used when verifying a digital signature or when encrypting data that can be decrypted with the corresponding private key.) that can be used to validate the private key (private key: The secret half of a cryptographic key pair that is used with a public key algorithm. Private keys are typically used when digitally signing data or decrypting data that has been encrypted with the corresponding public key.) that is associated with a digital signature. Digital certificates make it possible for digital signatures to be used as a way 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.
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How can I get my own digital signature?
If you try to digitally sign an Office document without a digital certificate, the Get a Digital ID dialog box appears, and you are asked to select how you want to get your own digital signature.
You have two options for getting a digital signature:
To learn more about each option, see the following sections.
Get a digital signature from a Microsoft partner
If you select the option Get a digital ID from a Microsoft partner in the Get a Digital ID dialog box, you are redirected to the Microsoft Office Marketplace, where you can purchase a digital certificate from one of the third-party certificate authorities (CAs) with an Office Marketplace listing.
If you plan to exchange digitally signed documents with other people, and you want the recipients of your documents to be able to verify the authenticity of your digital signature, it is a good idea to obtain a digital certificate from a reputable third-party certificate authority (CA).
Create your own digital signature
If you do not want to purchase a digital certificate from a third-party certificate authority, or if you want to digitally sign your document immediately, you can create your own digital certificate by selecting the Create your own digital ID option in the Get a Digital ID dialog box.
To create your own digital certificate
- In the Get a Digital ID dialog box, select Create your own digital ID.
Important The Get a Digital ID dialog box appears only if you attempt to digitally sign a document without a digital certificate.
- In the Create a Digital ID dialog box, type the following information to include in your digital signature:
- In the Name box, type your name.
- In the E-mail address box, type your e-mail address.
- In the Organization box, type the name of your organization or company.
- In the Location box, type your geographic location.
Note If you digitally sign a document by using a digital certificate that you created, and then you share the digitally signed file, other people cannot verify the authenticity of your digital signature. Your digital signature can be authenticated only on the computer on which you created the digital signature.
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