US Patent 9847979 Security and key management of digital content

Managing access to digital content within a particular domain, including: receiving the digital content at a first client device; decrypting the received digital content at the first client device using a first key; transcoding the digital content to another format; re-encrypting the transcoded content using a second key, wherein the second key is obtained by one of: (1) directly from a server; or (2) indirectly by deriving it locally based on information received from the server; and transmitting the re-encrypted content to a second client device, wherein the second client device obtains the second key and decrypts the re-encrypted content at the second client device.