The Validation Leg — v1 (order-of-magnitude survey)

Status: STARTED (v1, 2026-08-04). This is an analytical bound plus a literature survey — NOT a measured benchmark. It answers the question the storage leg deliberately left open (§7 of the working paper): what does validation cost, as a distinct resource leg of the fee-internalization framework? Confidence: order-of-magnitude only (uncertainty band ≈ 0.5×–5×).

1. What validation cost IS

Per full node, per block, validation is the CPU work of proving the block is legitimate before (and while) it is stored or pruned:

  1. Proof-of-work check — hash the 80-byte header below the target (trivial: one SHA256d ≈ microseconds; the expensive PoW is paid by miners, not validators).
  2. Block-structure rules — size/weight limits, merkle-root consistency, witness commitment, timestamp/version fields.
  3. Transaction validity — script execution and signature verification (the dominant term: ECDSA / Schnorr checks per input), UTXO-set availability (no double-spend), fee arithmetic, standardness.

The structural property that makes validation special: it is the only cost that is strictly unavoidable at any replication scale — every node pays it for every block since genesis, pruned or archival, and no node can "skip" validation and remain a full node. Storage can be pruned; bandwidth is one download per block; validation is CPU work repeated N times (once per node) and is not amortizable below one full pass per block per node.

2. Rough analytical bound (order of magnitude)

TermValueBasis
Blocks per year, R_blocks52,596model-spec.json (365.25 × 24 × 6)
Signature checks per block~3–10Ktypical block: 3–4K txs × ~2 inputs; dominated by ECDSA/Schnorr verifies
Verify throughput (modern hw)~10–30K sigs/slibsecp256k1, single-threaded, modern x86 (Bitcoin Core src/bench class of results)
Validation CPU per block~0.1–1 ssig-check-dominated; cross-checked by initial-sync delta below
Validation CPU per year per node~1.5–15 h52,596 blocks × 0.1–1 s
Amortized compute cost$0.10–0.50 / CPU-hnode budget C=$925/yr over ~9K h/yr, CPU share + electricity
Validation cost per node per year~$0.5–$51.5–15 h × $0.10–0.50; central ≈ $1–2/yr
Network-wide (N = 32K)~$16K–160K/yr× the ≥32K lower-bound census; central ~$32–64K/yr

Cross-check via initial sync. Full initial validation of ~1M blocks adds on the order of 6–24 h of CPU over an assumevalid-style sync on comparable hardware ⇒ 0.02–0.09 s/block averaged (I/O-bound, so a lower bound on CPU) — consistent with the 0.1–1 s/block estimate above for steady-state validation with an in-RAM UTXO cache (steady state is CPU-bound, sync is I/O-bound; the two brackets straddle the true value).

Key quantities carried in the model: R_blocks (52,596) and N (≥32K) are canonical in research/model-spec.json; the validation leg adds no new model constant — it is a resource-budget bound on C (the bundled $925/yr node cost), the same decomposition discipline as the bandwidth leg.

3. Reference literature

4. Uncertainty bands — explicit

5. Falsifiable claim (v1)

"Validation cost per full node per year is < $100 — bounded from above by the entire node hardware+operating budget C = $925/yr (model-spec v2.1.0), with a central order-of-magnitude estimate of ~$1–2/yr per node."

This claim is falsified if: (a) a measured benchmark shows steady-state validation CPU ≥ ~200 h/yr per node on reference hardware (⇒ ≥ $20–100/yr at the amortized rate — inside the $100 bound but outside the stated order of magnitude), or (b) a defensible full node census with per-node hardware data shows validation is a binding provisioning constraint (i.e., nodes are upgraded because of validation load, making the marginal cost the hardware delta, not the CPU-hours — the C-decomposition caveat in §7.2 row 3 of the working paper). Both directions are checkable against Bitcoin Core benchmarks and a hardware census; until either lands, the bound stands as the v1 value.

6. What this leg does NOT claim

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