A robust, computationally-efficient and secure system is described for streaming content from a server to a client device via the Internet or another digital network. Various aspects relate to automated processes, systems and devices for securing a media stream with efficient yet effective digital cryptography. In particular, content may be transmitted in transport stream (TS) format in which all packets are encrypted (e.g., using a cipher block chain), in which control packets are exempted from encryption (e.g., using an electronic codebook), or in any other manner.