Recently I came across few Oracle links which tells a lot about Data Masking. Here are few links which gives you a great idea about the data masking feature of Oracle and the usage. It also covers the licensing part too.
Oracle Data Masking Pack:
Oracle Data Masking Pack provides a comprehensive easy-to-use solution to share production data with internal and external entities while preventing sensitive or confidential parts of the information from being disclosed to unauthorized parties. The solution replaces sensitive data in databases with realistic-looking, scrubbed data based on masking rules and conditions. QA staff can now use real data to represent authentic application and database scenarios in their testing processes without violating privacy policies or laws.
Replacing Sensitive Data Using the Data Masking Pack:
This tutorial shows you how to identify sensitive data, select appropriate mask formats for the sensitive fields, apply the mask and then replace the sensitive fields in the production version.
This tutorial covers the following topics:
Managing the Data Masking Format Library
Identifying Sensitive Data for Masking
Creating Data Masking Definitions for Your Application Schema
Exporting Mask Definitions to XML
Importing Data Masking Definitions
Creating and Applying a User-Defined Mask
Refer the below link for more details and screen shots.
Oracle Data Masking Pack Demo:
Refer the below link for a demo on Data masking.