Maximum distance separable (MDS) matrix multiplication.
MDS matrices provide optimal diffusion for algebraic hash functions. Any k x k submatrix is invertible, so the associated linear code achieves the Singleton bound.
Three strategies are provided:
- Reed-Solomon coset evaluation via Bowers butterfly networks.
- An optimized variant that integrates coset shifts into twiddle factors.
- Karatsuba-style convolution for circulant matrices.