This is an important topic to raise. Post-quantum migration is moving from an abstract cryptographic concern into a real engineering and governance problem. NIST finalized FIPS 203, FIPS 204, and FIPS 205 in August 2024, and the EU has since published a coordinated transition roadmap. QuantumScan is also a useful early attempt to turn the discussion into an automated cryptographic inventory rather than waiting until migration becomes urgent.
The central point is valid: Arbitrum protocols should identify their classical public-key dependencies before a cryptographically relevant quantum computer exists.
However, several distinctions in the post and in the public scanner model need to be made much sharper if the output is intended to represent actual security risk rather than the presence of cryptographic patterns.
1. A detected primitive is not yet a vulnerability
The public scanner-core describes a contribution rule in essentially four fields:
regex pattern → targeted algorithm → severity → PQC alternative
That is useful for building a cryptographic inventory, but it is not yet a complete risk model.
A technically defensible assessment needs an additional context chain:
detected primitive → cryptographic function → reachable use → authority controlled → key/exposure state → attack preconditions → affected assets or protocol state → upgrade path → residual classical bypass → severity
This distinction matters because two occurrences of ecrecover, ECDSA, RSA, or an EIP-712 helper can have completely different consequences.
One may protect an active bridge administrator, upgrade authority, treasury, permit path, or smart-account owner. Another may be an unused library definition, a test, an unreachable compatibility branch, or a verifier whose result does not authorize any valuable state transition.
The scanner should therefore separate at least three outputs:
- Cryptographic Inventory - what primitive or construction was detected.
- PQC Migration Exposure - what must eventually be replaced or upgraded.
- Security-Critical Quantum Risk - what an attacker could actually authorize, forge, decrypt, or control under a defined quantum attack model.
Without that separation, a pattern count can be reproducible while the severity conclusion is still overstated.
2. DORA Article 50 and the 2030 date are incorrectly combined
The post states that DORA Article 50 requires financial entities, including DeFi protocols, to assess quantum risk by 2030.
That is not what Article 50 says.
DORA Article 50 is titled “Administrative penalties and remedial measures.” It defines supervisory, investigatory, sanctioning, and remedial powers. It does not establish a quantum-risk assessment requirement or a 2030 PQC deadline.
The 2030 date comes from a separate policy instrument: the EU coordinated roadmap for the transition to post-quantum cryptography. The roadmap says that Member States should begin transitioning by the end of 2026 and that critical infrastructures should transition as soon as possible, no later than the end of 2030.
Those are materially different statements:
- DORA Article 50: enforcement and remedial powers;
- EU PQC roadmap: transition policy and target dates.
The regulatory mapping should be corrected in both the article and any scanner report that automatically associates “DORA Article 50” with a 2030 PQC deadline.
3. “Harvest Now, Decrypt Later” is not the same as future signature forgery
The post combines TLS traffic, transaction batches, sequencer activity, oracle signatures, and bridge authorization under one HNDL description.
That merges two different threat classes.
Confidentiality / HNDL
An attacker records encrypted traffic today and attempts to decrypt it later after the public-key key-establishment mechanism becomes breakable.
This is where ML-KEM / FIPS 203 is relevant. ML-KEM is a key-encapsulation mechanism used to establish a shared secret.
Authentication / signature compromise
A digital signature is not ciphertext waiting to be decrypted.
The future quantum threat to ECDSA is the ability to compromise the signing authority or forge valid signatures once the relevant public-key problem becomes tractable. This is where ML-DSA / FIPS 204 or SLH-DSA / FIPS 205 is relevant.
For public blockchain data, this distinction is essential. Public transactions and public batch data are not confidential merely because they are signed. The relevant long-term risk is often future authorization forgery, not future decryption.
A scanner should therefore classify findings by cryptographic purpose:
KEY_ESTABLISHMENT / CONFIDENTIALITYDIGITAL SIGNATURE / AUTHORIZATIONHASH / COMMITMENTCONSENSUS OR PROOF PRIMITIVETRANSPORT AUTHENTICATIONUNKNOWN FUNCTION
“HNDL-exposed ECDSA permit” is not a precise category. A recorded permit signature is a signature artifact, not encrypted payload. Its risk depends on authorization semantics, nonce state, replay domain, validity period, key exposure, and whether the same authority remains usable when a quantum attacker becomes practical.
4. EIP-712 is an encoding and hashing standard, not a signature algorithm
EIP-712 defines typed structured-data encoding, hashing, and domain separation for signable messages.
It is not itself ECDSA.
An EIP-712 message may be authorized by ECDSA today, but the quantum exposure belongs to the actual signature and verification mechanism, not to the structured-data format.
Therefore a scanner finding _hashTypedDataV4 should say something like:
“EIP-712 signing surface detected; determine the actual signature validator and authority path.”
It should not automatically classify EIP-712 itself as a critical quantum-vulnerable primitive.
The EIP-712 layer may remain useful in a PQC system because the same structured message and domain-separation logic can be bound to a different signature scheme, provided the implementation defines the message encoding and verifier correctly.
5. Safe and ERC-4337 require implementation-level analysis
The statement that all Safe signing keys are secp256k1 is too broad.
Safe supports several signature types, including ECDSA signatures, pre-validated signatures, and contract signatures through EIP-1271. An EIP-1271 verifier can implement a different validation mechanism.
Likewise, ERC-4337 is not inherently an ECDSA protocol. ERC-4337 explicitly leaves the meaning of the signature field to the Smart Contract Account implementation. Account abstraction is therefore both:
- a possible location of classical ECDSA exposure; and
- one of the most practical migration surfaces for alternative signature schemes.
The correct scanner object is not:
ERC-4337 = Medium quantum risk
It is:
ERC-4337 account → validator implementation → active signature scheme → upgrade authority → fallback/recovery paths → residual classical bypass
A smart account is not quantum-resistant merely because it verifies ML-DSA in one module. If an ECDSA owner, module manager, guardian, recovery key, proxy administrator, or upgrade path can replace or bypass that validator, the classical root of authority still exists.
That authority graph is more important than the mere presence of a PQ verifier.
6. EIP-7702 is a useful migration building block, but it does not itself migrate an EOA root key to PQC
EIP-7702 allows an EOA to delegate execution to code, which can support richer authorization policies.
But the set-code transaction and authorization tuples are still authenticated with secp256k1 fields, and the specification recovers the authority through ecrecover.
So EIP-7702 can place programmable code in the account’s execution path, but it does not by itself remove the original classical root authority.
The existence of the later draft EIP-7851 makes this point especially clear: that proposal was introduced specifically to allow delegated wallet code to disable residual ECDSA authority permanently after bootstrap.
Therefore the original statement should be narrowed to:
EIP-7702 can help bootstrap programmable migration logic for EOAs, but it is not by itself a complete classical-to-PQC root-key migration.
7. ML-DSA is a cryptographic-role replacement for ECDSA, not an implementation-level drop-in replacement
ML-DSA and ECDSA both provide digital signatures, but that does not make ML-DSA a direct drop-in replacement inside an EVM contract.
The integration changes:
- public-key representation;
- signature size;
- calldata;
- storage;
- hashing and domain binding;
- verification cost;
- ABI;
- account-validator logic;
- key rotation;
- upgrade and recovery policy;
- wallet and hardware support;
- testing and standards-conformance requirements.
The draft EIP-8051 proposes ML-DSA verification precompiles precisely because efficient EVM verification is a separate engineering problem. EIP-8051 is still a draft, not a deployed universal EVM capability.
At the same time, Arbitrum has a particularly relevant route that should be discussed more clearly: Stylus provides a WASM execution environment interoperable with Solidity and is explicitly suited to compute-intensive cryptographic applications.
QuantumScan’s public repository now points to an ML-DSA verifier implemented as an Arbitrum Stylus contract. That is the strongest Arbitrum-specific direction in this work.
But its correct meaning is:
Arbitrum can host application-level post-quantum signature verification today through a Stylus verifier callable from Solidity.
It does not mean:
Arbitrum transactions, EOAs, bridges, sequencer operation, governance, and Ethereum settlement have all become post-quantum secure.
The Stylus verifier is therefore a concrete migration component, not an end-to-end quantum-safety proof.
8. Hybrid signatures are not automatically safe; the composition rule matters
The post describes parallel ECDSA + ML-DSA as the safe transition approach.
Hybrid authorization can be useful, but the security depends on the verifier semantics.
AND composition
ECDSA valid AND ML-DSA valid
This can preserve authorization security if one of the schemes remains secure, but it also creates larger signatures, higher verification cost, more complex key lifecycle, and additional availability and recovery requirements.
OR composition
ECDSA valid OR ML-DSA valid
This preserves backward compatibility, but it remains vulnerable through the classical ECDSA branch for as long as that branch can authorize the same action.
Migration / phased composition
A phased design may use:
- ECDSA to authorize initial registration of a PQ key;
- a time-locked or governance-controlled transition;
- dual signatures during a defined overlap;
- explicit disabling of the classical path;
- emergency recovery rules that do not silently restore ECDSA authority.
Every hybrid design must also bind both signatures to the same:
- message;
- chain ID;
- account;
- nonce;
- action;
- expiry;
- validator version;
- domain separator.
Otherwise downgrade, replay, cross-domain, or split-message failures can defeat the intended protection.
“Hybrid” should therefore be a structured migration state, not a blanket safety label.
9. The “18 Critical OpenZeppelin findings” are evidence of migration surface, not 18 demonstrated vulnerabilities
Running an OpenZeppelin repository through a pattern scanner and obtaining 18 matches is useful evidence that classical cryptographic constructs are present.
It does not, by itself, prove 18 critical vulnerabilities.
To make that claim, the report would need to distinguish:
- library definitions;
- production-reachable paths;
- inherited but unused code;
- tests and examples;
- wrappers;
- interface declarations;
- application-specific authority;
- upgradeability;
- active assets and permissions;
- actual quantum attack preconditions.
A more accurate label would be:
18 cryptographic inventory findings;18 migration-surface findings; or18 findings requiring contextual risk assessment.
The scanner can then elevate only the subset whose execution and authority context establishes a real security consequence.
That change would strengthen QuantumScan. It would make the tool auditable as an inventory layer while preventing inventory matches from being mistaken for confirmed vulnerabilities.
What an Arbitrum-specific PQC migration model should look like
The most important missing piece is that Arbitrum is not one cryptographic boundary.
It is a layered authorization, execution, ordering, bridging, and settlement system.
A useful migration analysis should follow the full path:
user key / wallet
→ L2 transaction entry
→ smart-account or contract validation
→ application permissions and upgrade paths
→ ArbOS / EVM / Stylus execution
→ sequencer ordering and batch publication
→ rollup assertions and dispute system
→ canonical bridge and cross-chain messages
→ Ethereum settlement and hard finality
Arbitrum’s own architecture documentation distinguishes immediate sequencer-based soft finality from hard finality obtained when batches and assertions are confirmed on Ethereum. It also shows that batches are posted to Ethereum and that canonical bridging crosses contracts on both chains. See Inside Arbitrum Nitro.
This creates several separate migration planes.
Plane A - Application and smart-account authorization
This is the part Arbitrum can experiment with now.
Possible components:
- ERC-4337 custom validators;
- EIP-1271 contract signatures;
- Safe modules;
- Stylus ML-DSA verification;
- high-value contract actions requiring dual signatures;
- PQC key registration and rotation;
- transaction limits and time-delayed migration.
This plane can become post-quantum-aware before Ethereum changes its native transaction signature scheme.
Plane B - Residual classical authority
Every PQ validator must be checked for a classical bypass:
- ECDSA owner;
- proxy admin;
- module manager;
- guardian;
- recovery key;
- upgrade authority;
- emergency pause authority;
- EIP-7702 residual EOA key;
- permit or delegated approval path;
- off-chain operator key.
If any of those can authorize the same critical state transition, the application is not fully PQ-authorized.
Plane C - L2 transaction envelope and protocol-level account authority
Even if an application validates ML-DSA internally, the surrounding transaction may still enter the chain through classical Ethereum-compatible transaction authentication.
That does not make the application-level verifier useless. It means the protection boundary must be stated correctly.
A contract can reject an action unless a PQ signature is present, while the chain itself still accepts classical transaction envelopes.
Plane D - Sequencer and operational transport
Sequencer soft-finality operations, feed authentication, RPC transport, TLS key establishment, and operational keys should be assessed separately.
Confidentiality/HNDL applies only where confidential encrypted material exists and remains valuable later.
Authorization risk applies where a signing key can order, authenticate, administer, upgrade, or otherwise control protocol behavior.
These are not interchangeable findings.
Plane E - Bridge, governance, oracle, and upgrade authority
The scanner should map each active authority separately:
- bridge contracts;
- gateway/router administration;
- rollup upgrades;
- security council or governance execution;
- oracle report verification;
- relayer authorization;
- treasury and emergency controls.
The question is not only “Which algorithm appears in the code?”
The question is:
“What exact state transition can this key authorize, how long will it remain authoritative, and what mechanism replaces or disables it?”
Plane F - Ethereum settlement dependency
Arbitrum hard finality and rollup settlement depend on Ethereum.
Therefore an Arbitrum application can become PQ-authorized before the whole settlement stack becomes post-quantum secure, but it cannot honestly claim end-to-end quantum resistance while the parent-chain transaction and consensus assumptions remain classical.
This dependency should appear explicitly in any Arbitrum PQC readiness report.
A stronger output model for QuantumScan
For Arbitrum and other EVM systems, I would replace a single quantum-risk score with a structured matrix:
| Field |
Meaning |
| Primitive |
ECDSA, ECDH, RSA, BLS, AES, hash, ML-DSA, ML-KEM, etc. |
| Cryptographic function |
Signature, key establishment, confidentiality, commitment, proof, transport |
| Execution plane |
Wallet, account validator, contract, bridge, oracle, sequencer, governance, parent chain |
| Reachability |
Active, conditional, unreachable, test-only, unknown |
| Authority |
What state, assets, permissions, or upgrade rights it controls |
| Public-key exposure |
Hidden, exposed, repeatedly exposed, not applicable, unknown |
| Authority lifetime |
Ephemeral, rotating, long-lived, permanent, unknown |
| Quantum threat |
HNDL, future forgery, search-speed reduction, migration debt |
| Upgradeability |
Immutable, proxy-upgradeable, module-replaceable, governance-controlled |
| Residual bypass |
Classical path remaining after PQ integration |
| Migration component |
ERC-4337 validator, EIP-1271 verifier, Stylus verifier, precompile, key rotation |
| Migration status |
Inventory only, PQ-capable, hybrid, classical disabled, end-to-end blocked |
| Evidence class |
Detected, derived, confirmed, unresolved |
| Severity |
Assigned only after the above context is established |
This would preserve the value of automated scanning while making the resulting claims technically precise.
Final assessment
The original post is right about the strategic direction:
- classical public-key dependencies should be inventoried now;
- account abstraction is an important migration surface;
- Arbitrum Stylus gives the ecosystem a practical place to test compute-intensive PQ verification;
- bridge, governance, wallet, and authorization keys need migration planning before a quantum emergency.
But several claims should be corrected:
- DORA Article 50 does not impose a 2030 PQC deadline;
- HNDL confidentiality is not the same as signature forgery;
- EIP-712 is not a signature algorithm;
- Safe and ERC-4337 are not intrinsically ECDSA-only;
- EIP-7702 does not by itself remove the classical EOA root key;
- ML-DSA is not an implementation-level drop-in replacement for ECDSA;
- hybrid security depends on AND/OR and downgrade semantics;
- pattern matches are migration findings, not automatically critical vulnerabilities.
The clearest Arbitrum path is therefore not “replace ECDSA everywhere with ML-DSA.”
It is:
inventory every cryptographic authority
→ classify its actual function and exposure
→ introduce PQ verification first at the smart-account/application layer
→ use Stylus where compute-heavy verification is appropriate
→ run an explicitly defined hybrid transition
→ eliminate residual classical bypasses
→ migrate bridge, governance, oracle, and operational authority
→ track the remaining Ethereum settlement dependency
→ claim end-to-end PQ security only when every authoritative layer supports it
If QuantumScan makes this distinction between primitive detection, migration exposure, and security-critical authority, it can become considerably more valuable than a pattern scanner. It can become a real cryptographic migration-assessment instrument for Arbitrum and other EVM systems.