MERCAT (which stands for Mediated, Encrypted, Reversible, SeCure Asset Transfers and is the name of our asset privacy protocol) is a library which provides the functionality of confidential transaction. It implements the technical whitepaper which is available at https://polymath.network/resources.
For an example of how this library can be used to create accounts and create confidential transactions, refer to mercat-cli. To view the test harness, refer to test harness. And finally, to use the cli to interact with Polymesh chain, refer to interactive cli.