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 It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired.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 ...

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

如果我的代码来自其他区域，该怎么办？ 某些数字代码适用于可能与帐户上的区域设置不匹配的特定国家/地区。 如果你的帐户与你的物理区域匹配，并且你的代码是从你所在地区的零售商处购买的，请确保设备上的区域也与你的物理位置匹配。 若要从 Xbox 主机执行此作，请执行以下作：

Signing your email messages with a digital ID helps to prove your identity and prevent message tampering.

了解如何在您的 Xbox 設定檔和 [Microsoft 帳戶] 中變更個人資訊，例如付款選項和設定檔詳細資料。

在Outlook 中，可以为电子邮件创建一个或多个个性化签名。 签名可以包括文本、链接、图片和图像 (，例如手写签名或徽标) 。

了解如何在移动设备、Windows 设备或 Xbox 主机上兑换 Microsoft/Xbox 礼品卡或其他代码。

Find out how to change your Xbox gamertag through a browser, on your Xbox console, or your Windows device.

The Microsoft Authenticator app helps you sign into your accounts when you're using two-step verification.