International Association
for Cryptologic Research

We introduce QARMAvii, a redesign of the tweakable block cipher QARMA to provide more robust security bounds and allow for longer tweaks, while keeping very similar latency and area values. The longer tweaks serve to address specific use cases and facilitate the design of modes of operation with higher security bounds. This is achieved by adopting new key and tweak schedules, and by making some changes to the 128-bit versions, as well as by performing a deeper security analysis.

The resulting cipher offers competitive latency and area in HW implementations.

Some of our results may be of independent interest. This includes new MILP models of certain classes of diffusion matrices, the comparative analysis of a full reflection cipher against an iterative half-cipher, and our boomerang attack framework.