There are many times that we have to do customization on top of AD RMS and use AD RMS SDKs. Microsoft has release the AD RMS SDK and Client 2.1.

Quick Summary:

 AD RMS SDK 2.1 eliminates the need for developers to write thousands of lines of specialized code in order to discover AD RMS servers, download and use AD RMS certificates, and manage AD RMS identities, greatly simplifying the integration process.

Also, AD RMS SDK and Client 2.1 provides a number of stellar updates over AD RMS SDK 2.0 including:

  • AD RMS SDK 2.1 and Client 2.1 fully support Windows Azure Active Directory Rights Management (AADRM)
  • A complete new set of APIs called File API to make it easy for solutions to build RMS support. See more details here
  • Critical feedbacks and bug fixes reported by RMS partners and customers
  • Support for the new Generic Protection infrastructure to support protection for all file types

More information here