In June of 2019 Microsoft added to OneDrive the new Personal Vault feature that lets you lock your files in the cloud. Initial or new service was only available in Australia, New Zealand and Canada.
Microsoft has announced its service worldwide October of 2019.
The new service offers a protected area in OneDrive where you can have access only with some authentication method or with a second authentication step, such as your fingerprint, a PIN, or a code sent to you via email or SMS.
Your locked files in Personal Vault have an extra level of security, keeping you safe when someone accesses your account or your device. The Personal Vault appears as a special folder in your account.
In Appliances with Windows 10, Microsoft uses το BitLocker για την encryption of files stored in Personal Vault. The contents of Personal Vault are encrypted during upload to Microsoft's servers.
Personal Vault is a free, unlimited feature for Office 365 subscribers users OneDrive users who do not have a subscription will be able to store up to three files in the protected folder.
But if you don't have an Office 365 Home or Personal subscription, you can put more than 3 files in one archive ZIP and upload them to Personal Vault to bypass the restriction.
OneDrive's Personal Vault is enabled by default. If you do not intend to use it and want to get rid of it, you can turn it off by following these steps:
Note: Disabling Personal Vault will delete all the files you have stored in the Personal Vault folder and cannot be recovered.
To disable the OneDrive Personal Vault,
Open the OneDrive Web site and sign in to the service with your account.
Click the settings gear icon to open the settings
Click on the "Options" link under "Settings"
In the Options, click the Personal Vault tab on the left and click Verify your identity on the right.
Verify your account with one of the available OneDrive methods.
Finally, click Disable.
You can reactivate it at any time by following the same path as mentioned above and with a click on the Enable Personal Vault.