Wijesinghe's ExpanderGraph-128 (arXiv:2603.12637) builds a block cipher from 3-regular expander graphs where every vertex performs the same Boolean function. Security comes from graph topology — the connectivity pattern — not from component sophistication.
The through-claim: structure can substitute for complexity. Traditional block ciphers achieve diffusion through carefully designed S-boxes and mixing operations, each individually complex. EGC128 achieves comparable security (147.3-bit differential bound at 10 rounds, extrapolating to 413 bits for the full 20-round cipher) using identical, simple operations arranged on an expander graph. The graph's spectral gap guarantees rapid mixing; the vertices don't need to be clever because their arrangement already is.
This inverts the usual design philosophy. AES achieves diffusion through the complexity of its MixColumns and SubBytes operations. EGC128 achieves it through the address of each operation — where it sits in the graph, not what it computes. The security proof moves from analyzing individual components to analyzing global connectivity, and the hardware footprint follows: 380 LUTs on FPGA, competitive with dedicated lightweight designs.
The broader pattern: when the structure does the work, the components can be simple. The same principle appears in neural networks (simple neurons, complex architecture), ant colonies (simple agents, complex trails), and immune systems (simple receptors, complex network). Sophistication lives in the wiring diagram, not the wire.