International Association
for Cryptologic Research

This paper presents NORX8 and NORX16, the 8-bit and 16-bit versions of the authenticated cipher NORX, one of the CAESAR candidates. These new versions are better suited for low-end systems---such as ``internet of things\'\' devices---than the original 32-bit and 64-bit versions: whereas 32-bit NORX requires 64 bytes of RAM or cache memory, NORX8 and NORX16 require just 16 and 32 bytes, respectively. Both of the low-end variants were designed to retain the security properties of the initial NORX and be fast on small CPUs.