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 It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired.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

Want to add a padlock to your email messages? You can use encryption and digital signatures in new Outlook, classic Outlook, and Outlook on the web for work or school accounts to increase the security of messages. Encrypting an email message in Outlook means it's converted from readable plain text into scrambled cipher text. Only the recipient who has the private key that matches the public ...

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

Learn how to sign in and create app passwords for Microsoft apps and devices that don't support two-step verification.

Troubleshoot slow game or app downloads on Xbox One Account error occurs when signing in to Xbox network

When you try to create a new signature linked to your own account (cloud signatures), you notice that the newly created signature gets deleted after a while or you may find that the signature does not sync up with Outlook Web App (OWA).

Open the app, go to the app's top-level menu, and then select Send feedback. After that, contact Support or go to the Microsoft Authenticator app forum and explain the problem you're seeing and the steps you tried.

With two-step verification, you'll get a security code to your email, phone, or authenticator app every time you sign in on a device that isn't trusted. Need more help?