We propose the B+C Conjecture: a unified framework grounding cryptographic hash hardness in algebraic graph theory (C: Cayley Graph Expanders) and thermodynamic physics (B: Landauer Principle). Applied to YiJing Hash v2. 0 (SL (2, F₁27), 8 Hou-Tian Ba-Gua generators): (C1) BSGS algebraic lower bound: Omega (1, 431) matrix multiplications. (C2) Expander Mixing Lemma: t >= 1, 370 steps for epsilon=2^-128 statistical indistinguishability. Empirically confirmed: SL (2, F₅) Cayley graph is Ramanujan (lambda₂/d=0. 809, exact computation). (B) Landauer weak bound (proven): any physical inverter dissipates >= 7. 35e-19 J. Independent of P vs NP. Landauer strong bound (open conjecture): thermal inaccessibility of erased information. Companion: YiJing Hash v1. 0 (doi: 10. 5281/zenodo. 20257027), v2. 0 (doi: 10. 5281/zenodo. 20257132).
Yao-Kai Kao (Sun,) studied this question.