Immutable X sometimes gets described as 'post-quantum' because its STARK proofs are hash-based. That is true of the proof. It is not true of the user's ECDSA secp256k1 signature, which is what actually moves the NFT. The label is doing more work than the cryptography.
Summary
Immutable X is a StarkEx-based L2 Validium for NFTs/gaming. The STARK proof system is hash-based (FRI) and considered PQ-leaning at the proof layer, but user transactions still rely on ECDSA secp256k1 and no NIST-PQC signature scheme is deployed. Centralized operator controls upgrades. PQC washing risk: marketing sometimes describes STARKs as 'post-quantum' without qualifying that user sigs remain Shor-breakable.
What the gates say
- Hybrid: FAIL. No hybrid plan on file.
- Evidence: PASS. Sources reconstructable by third party.
- Primitive naming: PASS. Named primitives at every scored sub-level.
Burn-vs-rescue policy on file
undeclared
Seven dimensions
Each dimension scores 0-100 internally; the weighted roll-up produces the QRI on the left. Open a row to read the sub-score detail.
1 Cryptographic Exposure 28 / 100
StarkEx + StarkNet L2 architecture.
ECDSA secp256k1 (user tx, EVM) · STARK proofs (FRI over prime field, hash-based) · Keccak-256FRI-based STARKs are hash-based and considered PQ-leaning (vs pairing-based SNARKs).
FRI-STARK is PQ-leaning but not NIST-standardized. No PQC signature scheme deployed.
2 HNDL Exposure 22 / 100
User ECDSA keys exposed on first tx. NFT holdings persist long-term.
NFT holdings often long-dormant (collectibles). Cold ECDSA keys persistent.
STARK proofs are hash-based and PQ-leaning for state transitions. User ECDSA sigs still Shor-breakable.
TLS for API. No PQC KEM.
3 Metadata & Privacy Exposure 20 / 100
Pseudonymous. NFT provenance is fully transparent.
Centralized StarkEx operator runs the mempool/order book.
Ethereum bridge visible; deposits/withdrawals linkable.
Non-private by design; low marginal retroactive risk.
4 Migration Architecture 42 / 100
STARK proof system is modular — FRI parameters, hash choice upgradable. StarkEx governance controls upgrades.
StarkEx L2 uses L1 Ethereum wallets for tx submission. L1 AA (ERC-4337) leverageable.
Multi-year StarkEx upgrades (StarkEx → zkEVM). Operator controls upgrades.
No published hybrid PQC envelope. STARK already PQ-leaning on proof side.
5 Deployment Execution 8 / 100
STARK proof system is hash-based/PQ-leaning, but this is not NIST PQC and user signatures remain ECDSA. Score credits FRI but flags conceptual gap.
No NIST PQC code in client.
No validator set — centralized operator.
No published PQC migration milestones.
StarkWare public about 'STARKs are post-quantum' but no user-sig PQC plan. Arguable PQC washing.
6 Supply Chain Vendor Readiness 8 / 100
7 Governance & Coordination 25 / 100
Centralized StarkEx operator. No validator set.
StarkEx operator-controlled upgrades. Transition from StarkEx to zkEVM in progress.
Immutable (James + Robbie Ferguson) + StarkWare. No named PQC lead.
No PQC-specific precedent.
The X + Y vs Z inequality
X (data shelf life): 5-10 (NFTs can be long-dormant; user sigs mostly short-lived)
Y (migration time): 10-15
Z10 (10% CRQC year): 2036 · Z50 (50%): 2041
Verdict: X+Y > Z (danger).
Four-scenario grid
| Scenario | Value preserved | Privacy preserved |
|---|---|---|
| quantum never | 100% | 100% |
| arrives suddenly pre migration | 10% | 15% |
| arrives slowly post migration | 80% | 70% |
| arrives slowly mid migration | 40% | 35% |
Peers in the rollup-L2 profile
Order-book view of the 9 chains closest to Immutable X by QRI.
Public artifacts used for this scorecard
Each entry below is a sub-score citation. Clicking the link takes you to the public source. A third party should be able to reconstruct every number on this page from these URLs in 48 hours.
StarkEx + StarkNet L2 architecture.
STARK proof system is hash-based/PQ-leaning, but this is not NIST PQC and user signatures remain ECDSA. Score credits FRI but flags conceptual gap.
Supply chain snapshot
A chain's supply chain cannot migrate faster than its slowest dependency. Zero PQC roadmaps in any of the four categories is a structural blocker, not a lagging indicator.
Analyst notes on the scoring
Small dim1 credit for PQ-leaning STARK proof system. Important caveat: STARK PQ-security is not the same as user key security. Band 2 Acknowledged due to StarkWare's public PQ discourse, but no signature-layer PQC plan found.
Scorecard metadata
- Profile: rollup-L2
- Scored: 2026-04-18 by
layerqu-v2-scoring-agent-3 - v1 reference:
chainscreen-v1-archive - QRI raw: 19 · after caps: 19
- Confidence interval: ±12
- PQC washing ratio: 1.1x
- Burn-vs-rescue: undeclared
Caps triggered
- Mosca (5a<20% → QRI max 60)
- Sutor (5d=0 → Migration Stage max 2)
- Preskill (several dims <3 artifacts × 0.5)
- Casado (3+ vendor tiles pqc=0 → migration_stage max 3)
- Hybrid gate FAIL → QRI cap 60