June 21, 2024
Pablo Garcia Fernandez - University of Luxembourg
NIST is planning a call for a tweakable variable-input-length strong pseudorandom permutation (VIL-SPRP), coined as “an Accordion mode”. In this paper, we survey tweakable VIL constructions, specially focusing on those based on the Hash-Encrypt-Hash paradigm (including HCTR and similar designs) in terms of their applicability as an Accordion mode, and discuss their efficiency and shortcomings. Furthermore, we also introduce an improved version that achieves Beyond Birthday Bound (BBB) security.
Workshop on the Requirements for an Accordion Cipher Mode 2024