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Certificate authority (CA) A certificate authority is an entity similar to a notary public. It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired. Top of Page Digital signature assurances The following terms and definitions show what assurances are provided by digital signatures. Authenticity The signer is ...

About digital signatures and certificates in Office, and buying a digital certificate from a certificate authority or create your own.

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Support for Windows 10, Office 2016 and Office 2019 has ended on October 14, 2025. Learn more about your options for Windows 10 or for Office.

注意: 请注意，Surface 商业设备的支持案例只能 联机 启动。 对于批量许可支持，请打开Microsoft 365 管理中心，选择“ 帮助 & 支持 ”，并搜索“管理批量许可”或提交 联机支持请求。 请不要忘记包括你的许可证 ID 或协议编号、你的联系人电话号码 & 电子邮件地址，以便我们可以联系你。 如果已有 ...

See how to view the details for signatures and certificates.

How to add a signature to your Word documents. You can also use the Signature Line command in Word to insert a line to show where to sign a document.