Secure Your Sandbox Data with Salesforce Data Mask

Salesforce Data Mask is a powerful new data security resource for Salesforce admins and developers. Instead of manually securing data and access for sandbox orgs, admins can use Data Mask to automatically mask the data in a sandbox.
This change applies to Lightning Experience in Enterprise, Performance, and Unlimited editions.
Data Mask uses platform-native obfuscation technology to mask sensitive data in any full or partial sandboxes. The masking process lets you mask some or all sensitive data with different levels of masking, depending on the sensitivity of the data. Once the data is masked, you can’t unmask it. This irreversible process ensures that the data is not replicated in a readable or recognizable way into another environment.
Data Mask is a managed package that you install in a production org. You then run the masking process from any sandbox created from the production org.