L2 network token
Arbitrum ARB
Arbitrum is an optimistic Ethereum L2 rollup whose entire production cryptographic stack is classical: ECDSA secp256k1 for EOAs, the centralized sequencer/batch-poster, and DAS store requests; BLS12-381 for AnyTrust DAC (Nova); and Ethereum L1 for bridge escrow, batch settlement, and BoLD fraud-proof arbitration. Offchain Labs has published no quantum risk assessment, cryptographic inventory, or migration roadmap, and no PQC primitive is deployed anywhere in the Nitro stack. The community has flagged quantum exposure in a forum technical overview, and external evaluators have produced independent assessments, but these are not project-authored. Architectural crypto-agility surfaces exist (EIP-7702, ERC-4337, Stylus WASM precompiles) but are latent and unused for quantum defense. The resulting Factor Score of 4.19 is capped by the absence of a public cryptographic inventory (Readiness & Risk Cap 10), yielding a QRI Score of 4.19 at Stage 1 (Quantum Risk Assessed). Arbitrum's quantum readiness is fundamentally inherited from and bounded by Ethereum L1's own classical migration timeline.
Roadmap OnlyECC-only spend authorizationBLS12-381 AnyTrust DACL1 bridge/settlement dependencyNo project-authored quantum risk assessmentNo PQC deploymentCrypto-agility surfaces present but unused for PQExternal assessment only
Category breakdown
QRI Factors
Algorithm & Implementation Assurance
0.5 / 20
Migration Mechanism, Governance & Ecosystem Coordination
0 / 15
Migration Status & Value-at-Risk
1 / 25
Production Cryptographic Protection
2.19 / 35
Security Assessment & Evidence Preparedness
0.5 / 5
Critical Quantum Blockers
- No public cryptographic inventory or quantum threat model published by Offchain Labs or the Arbitrum Foundation (Readiness & Risk Cap: 10).
- Active production spend authorization is entirely ECDSA secp256k1 (EOAs) with no PQC or hybrid path on mainnet (Readiness & Risk Cap: 40).
- The canonical Arbitrum-to-Ethereum bridge and rollup settlement depend on Ethereum L1, which remains ECDSA/classical, permitting unrestricted two-way flow of value into a non-PQ-secure system (Readiness & Risk Cap: 50).
- AnyTrust data availability (Arbitrum Nova) uses BLS12-381 threshold signatures, which are vulnerable to Shor's algorithm.
- Bridge escrow and governance are controlled by upgradeable proxy contracts under ECDSA multisigs (Arbitrum DAO + Security Council), which could be compromised independently of individual user key exposure.
Key Risks
- All EOAs that have sent a transaction on Arbitrum One have exposed secp256k1 public keys on-chain, creating a long-exposure, offline-attackable surface with no mitigation, freeze, or recovery path.
- The sequencer's ECDSA batch-poster key and DAS store-request signing key are single-signer classical keys; compromise would permit batch forgery/censorship until BoLD dispute resolution, which itself relies on ECDSA on Ethereum.
- Arbitrum Nova's AnyTrust DAC uses BLS12-381 threshold signatures, which Shor's algorithm breaks; DAC key compromise could undermine data availability and force chain recovery.
- The canonical bridge escrow and its upgrade authority are controlled by ECDSA multisigs (Security Council + DAO); a quantum-capable adversary compromising those keys could drain bridged assets independently of individual user-level key exposure.
- Rollup finality and fraud-proof arbitration settle on Ethereum L1, so even a hypothetical L2-level PQC deployment would remain capped by Ethereum's classical ECDSA settlement and bridge.
- No value-at-risk measurement exists for dormant/unmigratable exposed-key holdings vs. bridge-locked assets, making precise coverage unattestable and leaving all known pools unprotected.
- Arbitrum cannot independently achieve quantum readiness; it must depend on Ethereum L1's PQC migration, which targets core infrastructure by approximately 2029 but has no guaranteed timeline.
Assurance Notes
- Arbitrum has extensive classical security audits (Trail of Bits, OpenZeppelin, Quantstamp, Veridise; 2021–2026) covering Nitro, BoLD, Stylus, bridges, and core contracts. These are current and high-quality for classical scope but contain no post-quantum analysis or quantum-critical review. Audit freshness is scope-mismatched for quantum-critical properties.
- The classical cryptographic facts (ECDSA secp256k1 for EOAs/sequencer/batch-poster, BLS12-381 for AnyTrust DAC) are directly verifiable from the OffchainLabs/nitro source repository and official Arbitrum docs, giving high confidence in the vulnerability determination even absent a quantum-specific audit.
- Offchain Labs' research page lists 'post-quantum security' as a research area, but this is a research pointer with no dated milestones, code, specification, cryptographic inventory, or migration roadmap. No PQC announcement has been made in the trailing 12 months.
- Arbitrum possesses genuine crypto-agility surfaces — EIP-7702 EOA delegation (ArbOS 40 Callisto, live 2025-06-17), ERC-4337 account abstraction, and Stylus WASM custom precompiles — but no PQC primitive has been shipped on any of them and no migration document exists.
- BoLD's internal dispute cryptography uses collision-resistant hash functions and Merkle proofs (Grover-tolerant, not Shor-broken), but the dispute protocol ultimately arbitrates on Ethereum L1 via classical transactions, so the settlement dependency remains quantum-vulnerable.
- No formal quantum-specific incident-response playbook, no benchmark for PQ signature/verification costs in Arbitrum's execution environment, and no exchange/custody migration attestations were identified. These are note-only caveats given the absence of any PQ path to protect today.
- The quantum risk assessment reflected in this report is externally provided (community forum post, qrindex.org, independent evaluator analysis), not project-authored by Offchain Labs or the Arbitrum Foundation.
- Ethereum L1 has published a post-quantum roadmap with milestones (I*, J*, L*, M*) targeting core PQ infrastructure by approximately 2029, including EIP-8141 native account abstraction considered for Hegotá (2027). Arbitrum inherits L1 security and would benefit from L1 PQ migration, but no Arbitrum-specific PQ migration plan exists.
Non-Scoring Caveats
- EIP-7702, ERC-4337, and Stylus provide architectural crypto-agility that would make an application-layer PQC migration tractable, but no such migration has been specified, audited, or shipped. This is recorded as a note, not a score credit, because it does not currently protect any production value.
- Offchain Labs' research page mentioning 'post-quantum security' is a research-direction pointer with no dated milestones, code, or specification; treated as Very Low confidence research language.
- The community forum post 'Post-Quantum Cryptography Risk in Arbitrum Smart Contracts' is a secondary source authored outside Offchain Labs; it is directionally aligned with primary docs/code but is not an official project inventory or risk assessment.
- BoLD's hash-based Merkle commitments are more quantum-tolerant than pairing-based ZK schemes, but this does not offset the ECDSA settlement, sequencer, bridge, or DAC vulnerabilities.
- No formal performance benchmark exists for PQ signature/verification cost in Arbitrum's gas/fee market; noted only because no PQ path exists to benchmark.
- Optimism/Superchain has published a post-quantum roadmap for its L2 ecosystem, but Arbitrum is NOT a member of the Superchain and has no equivalent published plan.
- Ethereum L1's post-quantum roadmap (milestones I* through M*, targeting ~2029) would partially benefit Arbitrum through inherited account abstraction and PQ precompiles, but the timeline and mechanism for L2 inheritance remain undetermined.
Evidence record
Claims and Caveats
Security Assessment & Evidence Preparedness
Public cryptographic inventory of critical public-key mechanisms
Claim: Arbitrum/Offchain Labs has published no quantum threat model or cryptographic inventory enumerating critical public-key mechanisms and affected layers. A community forum post identifies some surfaces but is not a systematic project inventory.
Coverage basis: Non-PQ design with no project-authored inventory; community and external assessments exist but are not official.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical uncertainty · Score treatment: cap-applying
Quantum blocker: No public cryptographic inventory published by Offchain Labs or the Arbitrum Foundation (Readiness & Risk Cap: 10).
Assurance: Absence of a project inventory is confirmed by qrindex.org and the absence of any Offchain Labs publication; the forum post is a community-authored secondary source.
The forum post identifies ECDSA/ecrecover, EIP-712, bridges, sequencer, and governance as vulnerable, but is not a comprehensive or officially owned inventory. This absence triggers the Readiness & Risk Cap of 10.
Security Assessment & Evidence Preparedness
Public evidence record supporting the quantum assessment
Claim: Some evidence exists (open-source Nitro code, audit reports, forum discussion, external evaluations), but it is not organized as an evidence-backed quantum risk assessment by the project.
Coverage basis: Classical source code and audits exist; external quantum evidence records available but not project-endorsed.
Implementation score: 0.25 · Evidence confidence: High
Issue classification: assurance-only caveat · Score treatment: score-reducing
Assurance: Code and classical audits are verifiable and current for classical scope but contain no quantum analysis. External evaluators have assembled evidence records.
0.25 reflects that raw evidence exists and external assessments have been produced, but no project-authored quantum evidence record exists.
Production Cryptographic Protection
Spend authorization / transaction signatures are PQC or hybrid-PQC on mainnet
Claim: All transaction spend authorization uses ECDSA secp256k1 via standard Ethereum EOAs; no PQC or hybrid signature path exists on mainnet.
Coverage basis: ECC-only spend authorization, verifiable in Nitro source (Geth fork) and official docs.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: Active production spend authorization remains entirely ECDSA-only (Readiness & Risk Cap: 40).
Assurance: Directly verifiable from source code, docs, and third-party key format documentation (Dfns confirms ECDSA secp256k1 for Arbitrum One).
This is the dominant quantum-critical vulnerability for all Arbitrum One users.
Production Cryptographic Protection
Account, address, public-key exposure, and key-derivation design
Claim: EOAs expose secp256k1 public keys on first transaction; reused/dormant transacted EOAs are long-exposure attackable with no PQ/hybrid control or deprecation mechanism.
Coverage basis: Long-exposure ECC public keys with no mitigation path.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: Material long-exposure quantum-vulnerable value (transacted EOAs with exposed public keys) exists with no migration, freeze, or recovery path (Readiness & Risk Cap: 55).
Assurance: Ethereum-style EOA public-key exposure is standard and well-documented. Any EOA that has sent a transaction has its public key permanently derivable on-chain.
Long-exposure attack window: public keys are permanently visible on-chain for any transacted EOA.
Production Cryptographic Protection
Consensus-critical authentication (sequencer, validators, DAC)
Claim: Sequencer/batch-poster uses ECDSA for signing batch transactions and DAS store requests; BoLD validators bond and post commitments with Ethereum-format (ECDSA) keys; AnyTrust DAC uses BLS12-381 threshold signatures.
Coverage basis: Classical ECDSA and BLS authentication for all consensus-critical roles.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: Sequencer and DAC authentication are ECDSA/BLS-only; BoLD validation settles via ECDSA on Ethereum (Readiness & Risk Cap: 70).
Assurance: DAS docs confirm the batch-poster signs das_store requests with an ECDSA key; AnyTrust protocol docs confirm BLS12-381 aggregated signatures for DACerts; BoLD overview confirms L1 settlement.
Arbitrum One uses a centralized sequencer (Offchain Labs). BoLD enables permissionless validation but fraud proofs are arbitrated on Ethereum L1 with classical infrastructure.
Production Cryptographic Protection
State-integrity and data-availability mechanisms
Claim: BoLD uses collision-resistant hash/Merkle commitments (Grover-tolerant, not Shor-broken), but settlement arbitrates on Ethereum L1 (ECDSA) and AnyTrust DA uses BLS12-381 signatures for Data Availability Certificates.
Coverage basis: Hash-based internal commitments with quantum-vulnerable L1 settlement and BLS DAC.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: State settlement and AnyTrust DA rely on ECDSA/BLS on a quantum-vulnerable path (Readiness & Risk Cap: 70).
Assurance: BoLD paper (AFT 2024) confirms the security assumption is collision-resistant hashes, which is comparatively quantum-tolerant; however the rollup's one-step proof verification executes on Ethereum smart contracts under ECDSA settlement.
The hash-based BoLD internal commitments prevent total state-integrity collapse but do not rescue the overall layer due to L1 settlement and BLS DAC dependencies.
Production Cryptographic Protection
Privacy and proof layers (ZK assumptions, note encryption, shielded state)
Claim: Arbitrum One/Nova have no native privacy layer or shielded state; fraud proofs are hash/Merkle-based, not ZK/pairing-based.
Coverage basis: No privacy layer; optimistic (non-ZK) proof system.
Implementation score: 0 · Evidence confidence: High
Issue classification: none · Score treatment: not applicable
Assurance: BoLD's cryptographic assumptions are collision-resistant hashes (verified in the AFT 2024 paper), not pairings.
Production Cryptographic Protection
P2P transport, node identity, and peer authentication
Claim: Nitro nodes use standard go-ethereum P2P (devp2p) with classical cryptography for node identity, but P2P node identity is not consensus, spend, bridge, or custody-critical.
Coverage basis: P2P identity is non-critical to asset ownership or consensus finality.
Implementation score: 1 · Evidence confidence: High
Issue classification: none · Score treatment: not applicable
Assurance: Nitro is a Geth fork using standard Ethereum devp2p; P2P identity is not a fund-control or consensus-authentication path.
Production Cryptographic Protection
Critical wallet, custody, HSM, and hardware-wallet workflows
Claim: No PQ/hybrid wallet, custody, HSM, or hardware-wallet workflow exists; all user and institutional signing relies on standard ECDSA Ethereum wallets.
Coverage basis: No PQ wallet/custody path.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Assurance: No PQC wallet support exists anywhere in the Arbitrum ecosystem. Standard Ethereum wallet infrastructure (MetaMask, Safe, Ledger, Trezor) all use classical ECDSA.
Migration Status & Value-at-Risk
Percentage of economically relevant value-at-risk protected from quantum key-recovery attacks
Claim: No value is migrated or protected; all circulating supply, bridged assets, treasuries, and exposed-key EOAs remain quantum-vulnerable. Coverage is <25% (effectively 0%).
Coverage basis: <25% coverage — experimental/negligible protection.
Implementation score: 0.05 · Evidence confidence: Medium
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: Material long-exposure quantum-vulnerable value exists with no migration, freeze, deprecation, burn, recovery, or policy path (Readiness & Risk Cap: 55).
Assurance: Exact coverage cannot be precisely measured from public data; Medium confidence reflects the inability to distinguish active vulnerable value vs. bridged L1-collateralized value without primary analytics. Implementation score of 0.05 corresponds to the <25% tier (score 1 out of 20).
Actual coverage is 0% — no PQ protection exists for any value pool.
Migration Status & Value-at-Risk
Critical wallets migrated, protected, or inherently PQ-native
Claim: Treasuries, bridge escrow, DAO treasury, and Security Council multisig are all ECDSA-controlled; none are migrated or PQ-native.
Coverage basis: No critical wallet migration.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: Major value pool (bridge escrow, DAO treasury, Security Council) remains quantum-vulnerable with no migration path (Readiness & Risk Cap: 70).
Assurance: DAO and Security Council governance structure is documented in official Arbitrum Foundation docs. Contract addresses are publicly verifiable.
Bridge escrow is controlled by upgradeable proxy contracts. Security Council has emergency upgrade authority. Both use classical ECDSA.
Migration Status & Value-at-Risk
Legacy vulnerable pools/accounts/UTXOs/contracts identified and addressed
Claim: No formal identification, measurement, deprecation, freeze, or burn policy exists for long-exposure or dormant vulnerable EOAs.
Coverage basis: No legacy-pool identification.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Assurance: No public position from Offchain Labs or the Arbitrum Foundation on dormant L2 funds in a quantum scenario.
All transacted EOAs on Arbitrum One have exposed public keys. No burn, freeze, or deprecation mechanism for these accounts exists in the protocol.
Migration Mechanism, Governance & Ecosystem Coordination
Public migration or protection roadmap
Claim: No Arbitrum-specific PQ migration roadmap, activation criteria, or dependencies have been published by Offchain Labs or the Arbitrum Foundation.
Coverage basis: No roadmap.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical uncertainty · Score treatment: score-reducing
Assurance: Trailing-12-month PQC announcement count from Offchain Labs / Arbitrum Foundation is zero. Note: Optimism/Superchain has published a PQ roadmap, but Arbitrum is NOT a Superchain member.
Ethereum L1 has a PQ roadmap (milestones I*–M*, ~2029), but no mechanism for L2 inheritance has been specified for Arbitrum.
Migration Mechanism, Governance & Ecosystem Coordination
Migration accessibility and defaults
Claim: No PQ/hybrid account creation, wallet tooling, custody path, education, or migration prompts exist; EIP-7702/ERC-4337/Stylus are available but no PQ path uses them.
Coverage basis: No migration accessibility.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Quantum blocker: Users can still create new quantum-vulnerable high-value accounts by default (Readiness & Risk Cap: 60).
Assurance: EIP-7702 (live 2025-06-17) and Stylus provide latent agility, but no PQ primitive has been shipped on them.
Migration Mechanism, Governance & Ecosystem Coordination
Migration enforcement and coordination
Claim: No enforcement mechanisms (deprecation, freeze, disabled legacy signing, restricted withdrawals) or exchange/custody/bridge coordination for PQ migration exist.
Coverage basis: No enforcement.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Assurance: No evidence of any PQ enforcement or coordination activity.
Migration Mechanism, Governance & Ecosystem Coordination
Emergency disclosure, incident-response, or governance process for quantum vulnerabilities
Claim: No quantum-specific emergency disclosure or incident-response process exists. General DAO + Security Council governance exists but does not address quantum attack scenarios.
Coverage basis: No quantum-specific IR.
Implementation score: 0 · Evidence confidence: High
Issue classification: assurance-only caveat · Score treatment: confidence-only
Assurance: General governance processes exist (DAO + Security Council), but no quantum-specific IR playbook was identified. Per QRI rules, the absence of a quantum-specific IR playbook is an assurance-only caveat that does not independently create a quantum-vulnerable path (the paths are already vulnerable from ECDSA/BLS usage).
Algorithm & Implementation Assurance
Uses NIST-standardized or broadly reviewed PQC/hybrid algorithms
Claim: No NIST FIPS 203/204/205 PQC primitive is deployed anywhere in Arbitrum's production stack.
Coverage basis: No PQC algorithms.
Implementation score: 0 · Evidence confidence: High
Issue classification: quantum-critical vulnerability · Score treatment: score-reducing
Assurance: Nitro source grep confirms no ML-DSA/ML-KEM/SLH-DSA/Falcon/XMSS/SPHINCS+ implementation.
Algorithm & Implementation Assurance
Independent cryptographic and implementation audit of quantum-critical scope
Claim: No audit addresses post-quantum algorithms; all existing audits (Trail of Bits, OpenZeppelin, Quantstamp, Veridise) are classical-scope only.
Coverage basis: No quantum-scope audit.
Implementation score: 0 · Evidence confidence: High
Issue classification: assurance-only caveat · Score treatment: score-reducing
Assurance: Audits are current and high-quality for classical scope (2021–2026) but contain no quantum-critical review. This is expected given no PQ implementation exists.
Algorithm & Implementation Assurance
Open-source, reproducible implementation
Claim: Nitro and its contracts are open-source and reproducible, but there is no PQC implementation to be open-source.
Coverage basis: Open-source classical stack only; no PQ code exists.
Implementation score: 0 · Evidence confidence: High
Issue classification: none · Score treatment: not applicable
Assurance: Nitro is a public Geth fork; reproducibility exists for classical code but there is no PQ code to evaluate.
Algorithm & Implementation Assurance
Parameter agility and future upgrade path documented
Claim: EIP-7702 EOA delegation, ERC-4337, and Stylus WASM precompiles provide crypto-agility surfaces, but no PQC-specific parameter agility or upgrade path is documented.
Coverage basis: Latent agility, no PQC documentation.
Implementation score: 0.25 · Evidence confidence: High
Issue classification: none · Score treatment: note-only
Assurance: EIP-7702 (ArbOS 40 Callisto, 2025-06-17) and Stylus provide genuine architectural agility, but no PQ primitive or parameter set has been specified or shipped. Partial credit reflects the agility surface, not quantum protection.
Algorithm & Implementation Assurance
Stateful-signature safety and side-channel/fault-injection considerations
Claim: No PQC signatures (stateful or otherwise) are used, so no anti-reuse or signing-state discipline exists.
Coverage basis: No PQC signature implementation.
Implementation score: 0 · Evidence confidence: High
Issue classification: none · Score treatment: not applicable
Algorithm & Implementation Assurance
Performance and resource-impact analysis for PQ deployment
Claim: No performance/resource analysis exists for PQ signatures in Arbitrum's execution environment.
Coverage basis: No PQ performance analysis.
Implementation score: 0 · Evidence confidence: High
Issue classification: assurance-only caveat · Score treatment: note-only
Assurance: No PQ path exists to benchmark, so this is note-only rather than score-reducing.
PQ performance impact on L2 gas costs, calldata size (for L1 posting), and node requirements would be significant considerations for any future migration.
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