Authenticated Streamwise On-line Encryption

In Blockwise On-line Encryption, encryption and decryption return an output block as soon as the next input block is received. In this paper, we introduce Authenticated Streamwise On-line Encryption (ASOE), which operates on plaintexts and ciphertexts as streams of arbitrary length (as opposed to fixed-sized blocks), and thus significantly reduces message expansion and end-to-end latency. Also, ASOE provides data authenticity as an option. ASOE can therefore be used to efficiently secure resource-constrained communications with real-time requirements such as those in the electric power grid and wireless sensor networks. We investigate and formalize ASOE\u27s strongest achievable notion of security, and present a construction that is secure under that notion. An instantiation of our construction incurs zero end-to-end latency due to buffering and only 48 bytes of message expansion, regardless of the plaintext-size