{"id":"sibling-direction-matters","text":"Proof siblings are tagged \"left\" or \"right\" because SHA-256 concatenation is order-dependent — `H(A||B) != H(B||A)` — so swapping sibling position produces a different parent hash and verification fails.","truth_value":"IN","source":"entries/2026/05/29/topic-merkle-proof-security-model.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"sibling-direction-matters","truth_value":"IN","reason":"premise"}]}}