Pre-release notice:
The Quantum Readiness Index is still being reviewed and refined. Reports may include rough edges, including incomplete and/or incorrect coverage.

Post-quantum L1 chain

Quantum Resistant Ledger QRL

Quantum Resistant Ledger (QRL) is a PQ-native Layer-1 blockchain that launched in June 2018 with IETF-specified, NIST-approved XMSS (NIST SP 800-208) hash-based post-quantum signatures from the genesis block. Because the native asset has never had a classical ECC/BLS/Schnorr/EdDSA ownership namespace, ECC-to-PQC migration is complete by design for the native scope. Spend authorization, address design, key derivation, state integrity, and critical wallet/custody paths (including Ledger hardware wallet support) all use PQ-secure XMSS. The legacy Ethereum ERC-20 token is a retired, separate artifact with no active bridge or redeemable path to native QRL. Independent audits from Red4Sec (2018), x41 D-Sec (2018), and Halborn (March 2026) validate the implementation, with the Halborn audit finding zero cryptographic vulnerabilities in the current PQ cryptography library. QRL 2.0 (Project Zond) is a future PoS upgrade migrating from one PQ-secure system (XMSS) to another (ML-DSA-87/SPHINCS+) and does not represent a current quantum-readiness gap. The P2P layer uses classical cryptography for node identity but is not spend, consensus, bridge, or custody-critical and is treated as satisfied by design. No current quantum-critical vulnerabilities or unverifiable quantum-critical claims are identified in the evaluated production scope.

PQ-NativePQ-Resistant
Stage 4
Confidence Medium
Urgency [No Action Needed]
Review Status Draft
Evaluated 2026-06-01
Scope Native QRL L1 asset and protocol on the QRL PoW mainnet (v4.0.x). The legacy Ethereum ERC-20 token is a separate, non-native scope. The QRL 2.0 (Zond) PoS testnet is a future upgrade and is evaluated only as roadmap context.
AI-generated report. This report was produced by the evaluator and synthesis pipeline. Review status: draft.

Category breakdown

QRI Factors

Algorithm & Implementation Assurance 19.5 / 20
Migration Mechanism, Governance & Ecosystem Coordination 15 / 15
Migration Status & Value-at-Risk 25 / 25
Production Cryptographic Protection 35 / 35
Security Assessment & Evidence Preparedness 5 / 5

Critical Quantum Blockers

  • No critical quantum blocker analysis returned.

Key Risks

  • XMSS statefulness requires users to track one-time signature (OTS) indices. OTS exhaustion permanently disables signing for that address if a replacement address is not created. This is an inherent property of stateful hash-based signatures and is mitigated by QRL wallet tooling and Ledger integration, but remains an operational risk distinct from quantum attack.
  • The P2P networking layer currently does not use post-quantum cryptography for node identity or peer authentication. While this does not threaten asset ownership, spend authorization, or consensus (satisfied by design per QRI), a quantum adversary could theoretically target the P2P layer for eclipse or denial-of-service attacks. ML-KEM integration for the P2P layer is in early development as of May 2026.
  • The current mainnet audits (Red4Sec 2018, x41 D-Sec 2018) are approximately 8 years old. The XMSS cryptographic design is verifiable from NIST standardization, open-source code, and mainnet evidence, but the implementation has not undergone a recent end-to-end mainnet audit. The 2026 Halborn audit covers the crypto library intended for QRL 2.0, not the current mainnet node codebase directly.
  • The QRL 1.x to QRL 2.0 migration design (smart-contract-based, snapshot-driven, user-initiated claim) is documented in draft form but not yet finalized or tested on mainnet. Since both systems are PQ-secure, this is a PQ-to-PQ transition risk rather than a quantum-attack risk for the current scope.

Assurance Notes

  • The 2018 audits (Red4Sec, x41 D-Sec) are stale but remain relevant to the current PoW mainnet XMSS design. The XMSS implementation is verifiable from open-source code, mainnet evidence, and NIST SP 800-208 standardization.
  • The Halborn audit (March 2026) validates the qrypto.js cryptography library implementing ML-DSA-87 and Dilithium5 for QRL 2.0. While it covers a future upgrade, it provides current independent assurance for the project's PQ cryptography implementation practices. All 13 findings were Informational with zero cryptographic vulnerabilities.
  • QRL's P2P networking layer currently uses classical cryptography for node identity. This is satisfied by design per QRI Section 7 because all asset-spending authorization is PQ-signed on device and P2P identity is not consensus, spend, bridge, or custody-critical. ML-KEM implementation for P2P is in development as of May 2026.
  • XMSS stateful-signature operational risk (OTS key exhaustion) is mitigated by wallet tooling and documentation but remains an inherent product caveat. Funds in fully-exhausted wallets are permanently lost.
  • No formal quantum-specific incident-response playbook has been published, but QRL has security contacts (support@theqrl.org, press@theqrl.org) and has demonstrated responsiveness to external audit findings across multiple engagements.
  • QRL 2.0 (Project Zond) Testnet V2 launched March 2026 with ML-DSA-87 and plans for SPHINCS+ post-mainnet. This is a PQ-to-PQ upgrade that does not affect current mainnet quantum-attack readiness. Mainnet launch is contingent on audit completion.
  • Performance/resource analysis for XMSS is documented (approximately 3KB transaction size, longer key generation times) in the GitHub README, but no formal independent benchmark has been published for the production network. The network has operated since 2018 with approximately 900 active nodes globally, demonstrating practical viability.

Non-Scoring Caveats

  • Legacy ERC-20 QRL token on Ethereum: Per official project documentation, QRL operates on its own independent L1 blockchain and is NOT an ERC-20 token. The ERC-20 contract (0x697beac28B09E122C4332D163985e8a73121b97F) was a placeholder that was migrated 1:1 to the native mainnet starting in 2018 via a burn-address process. The exact percentage of unmigrated ERC-20 tokens remaining is not independently verified, but any residual balances do not represent native QRL and cannot expose the native mainnet to quantum attack. No active bridge or redeemable path links the ERC-20 to native QRL as of the evaluation date.
  • XMSS stateful-signature operational risk: XMSS requires users to track OTS key indices. Exhausting all OTS keys without creating a new wallet results in permanent loss of signing capability for that address. QRL wallet tooling tracks OTS state, and Ledger hardware wallet support provides additional protection. This is an operational UX consideration, not a quantum-attack vulnerability. QRL 2.0 plans to introduce stateless SPHINCS+ signatures to address this.
  • QRL 1.x to QRL 2.0 migration: A PQ-to-PQ migration from the current XMSS-based PoW mainnet to the ML-DSA-87-based PoS Zond mainnet is planned (smart-contract-based, user-initiated claim process). This is a future upgrade between two PQ-secure systems and does not represent an ECC-to-PQC migration gap in the current scope.
  • The P2P networking layer currently uses classical cryptography for node identity. While this does not threaten asset ownership, spend authorization, or consensus, a quantum adversary could theoretically target the P2P layer for eclipse or denial-of-service attacks. ML-KEM integration for the P2P layer is in early development as of May 2026.

Evidence record

Claims and Caveats

Security Assessment & Evidence Preparedness

Public cryptographic inventory and quantum threat model

Claim: QRL is PQ-native with XMSS from genesis. Whitepaper, documentation, and GitHub provide full cryptographic inventory. No classical native ownership namespace exists.

Coverage basis: PQ-native native asset; complete-by-design

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Documentation and whitepaper are public and comprehensive. Open-source code repository confirms XMSS-only signature scheme.

Security Assessment & Evidence Preparedness

Public evidence record supporting the assessment

Claim: Multiple independent audits (Red4Sec, x41 D-Sec, Halborn), open-source code, mainnet explorer, and NIST standardization provide public evidence.

Coverage basis: PQ-native native asset; complete-by-design

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Multiple audits across different auditors and timeframes. Halborn (2026) is current for crypto library. Red4Sec and x41 D-Sec (2018) are stale but relevant for mainnet XMSS design.

Production Cryptographic Protection

Spend authorization / transaction signatures

Claim: All native QRL transactions use XMSS (NIST-approved, IETF-specified) hash-based post-quantum signatures. No ECDSA, EdDSA, BLS, or Schnorr signatures exist for native spend authorization.

Coverage basis: PQ-native; mandatory XMSS from genesis block

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: XMSS implementation is open-source and verifiable. Audited by x41 D-Sec (2018) specifically for XMSS cryptography and Ledger code. Mainnet blocks since June 2018 confirm XMSS-only signatures.

Production Cryptographic Protection

Account, address, public-key exposure

Claim: QRL addresses use an extensible address format with XMSS public keys built in from genesis. No classical address types or key-derivation paths exist. No long-exposure ECC public keys are present on the native chain.

Coverage basis: PQ-native; XMSS-based address format only

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Address format is documented as 'extensible address format with quantum security built in from the genesis block.' No classical address namespace exists on the native chain.

XMSS public keys embedded in addresses are hash-based and quantum-resistant. No ECC public-key exposure exists for native accounts.

Production Cryptographic Protection

Consensus-critical authentication

Claim: QRL mainnet uses Proof-of-Work (cryptonight, later upgraded to randomX via QIP-009). No validator signatures, BLS threshold signatures, VRFs, or finality signatures exist in the consensus mechanism.

Coverage basis: PoW consensus; no validator authentication applicable

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: PoW consensus is hash-based and not vulnerable to Shor's algorithm. RandomX (upgraded from cryptonight) was audited by x41 D-Sec. The consensus mechanism does not rely on quantum-vulnerable digital signatures.

Production Cryptographic Protection

State-integrity and data-availability mechanisms

Claim: QRL uses hash-based state commitments. No KZG commitments, pairing-based proofs, or quantum-vulnerable accumulators are used in the protocol. Supply integrity is bound by hash-based signatures and Merkle tree structures.

Coverage basis: Hash-based state; no pairing/KZG dependencies

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: QRL's state integrity relies on hash-based Merkle trees and XMSS signatures. No quantum-vulnerable pairing or KZG assumptions exist. Quantum computers cannot break hash preimage resistance at a scale that threatens chain integrity.

Production Cryptographic Protection

Privacy and proof layers

Claim: QRL is a transparent ledger with no shielded transaction privacy layer, ZK proofs, note encryption, viewing keys, or stealth addresses. The ephemeral messaging layer uses Dilithium and Kyber but is not a transactional privacy layer.

Coverage basis: Not applicable - no privacy layer

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

QRL does support ephemeral messaging using Dilithium and Kyber, but this is not a privacy layer for transaction shielding.

Production Cryptographic Protection

P2P transport, node identity, and peer authentication

Claim: QRL's P2P layer for node discovery and peer communication currently uses classical cryptography. Node identity in the P2P mesh is not spend-authorization, consensus, bridge, or custody-critical.

Coverage basis: Satisfied by design; P2P identity not asset-critical

Implementation score: 1 · Evidence confidence: High

Issue classification: operational/product caveat · Score treatment: note-only

Assurance: P2P classical cryptography could theoretically enable eclipse or DoS attacks by a quantum adversary, but such attacks cannot forge transactions, steal assets, or compromise consensus finality. ML-KEM integration is planned as a defense-in-depth improvement.

QRL Weekly (2026-May-15) states: 'ML-KEM implementation has begun, it will be used in P2P layer.' This confirms the current P2P layer has not yet been upgraded to PQC but also that the project is actively addressing this as a non-critical enhancement.

Production Cryptographic Protection

Critical wallet, custody, HSM, signer, and hardware-wallet workflows

Claim: QRL supports XMSS-based wallets on web, desktop (Windows/Mac/Linux), mobile (iOS/Android), and Ledger hardware wallets (Nano S, Nano X, Nano S+). All custody paths use PQ-secure XMSS signatures.

Coverage basis: PQ-native; all wallet paths use XMSS

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Ledger hardware wallet support for a stateful PQ signature scheme (XMSS) is a significant operational achievement. The x41 D-Sec audit (2018) covered Ledger code specifically.

Migration Status & Value-at-Risk

Percentage of economically relevant value-at-risk protected

Claim: QRL is PQ-native. 100% of native QRL value-at-risk is protected by XMSS from genesis. No classical native ownership namespace exists. The legacy ERC-20 token is a separate scope with no active bridge to native QRL.

Coverage basis: PQ-native; complete-by-design; ≥99% native coverage

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Mainnet explorer (explorer.theqrl.org) confirms active block production (block height > 2.5M as of 2026). Emission at approximately 74% of max supply (78.3M of 105M). All on-chain value is PQ-protected by construction.

Exact percentage of unmigrated ERC-20 tokens is not independently verified but does not affect native QRL scope. Even 100% unmigrated ERC-20 tokens would represent a separate legacy artifact, not native QRL value-at-risk.

Migration Status & Value-at-Risk

Critical wallets migrated, protected, or inherently PQ-native

Claim: All native QRL wallets (treasuries, exchanges, custodians, foundations) use XMSS addresses. The protocol design prevents creation or import of classical-vulnerable native addresses.

Coverage basis: PQ-native; all native wallets are XMSS-based by protocol requirement

Implementation score: 1 · Evidence confidence: Medium

Issue classification: none · Score treatment: not applicable

Assurance: Medium confidence because specific exchange/custodian attestations are not individually documented in available evidence. However, the protocol-level enforcement (only XMSS addresses can hold native QRL) makes classical custody impossible by construction.

Migration Status & Value-at-Risk

Legacy vulnerable pools/accounts/UTXOs/contracts are identified, measurable, deprecated, migrated, frozen, or proven not to exist by design

Claim: No classical-vulnerable native QRL addresses, UTXOs, or accounts exist. The ERC-20 token is a separate legacy artifact that has been migrated/burned. No active bridge links ERC-20 to native QRL.

Coverage basis: PQ-native; legacy classical namespace proven not to exist by design

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Multiple official sources confirm QRL is an independent L1 blockchain, not an ERC-20 token. The EnQlave/wQRL project has been retired. No active bridge or two-way wrapper to Ethereum or any quantum-vulnerable system exists for native QRL as of the evaluation date.

Migration Mechanism, Governance & Ecosystem Coordination

Public migration or protection roadmap

Claim: QRL is PQ-native; ECC-to-PQC migration is not applicable. The QRL 1.x to QRL 2.0 (Zond) upgrade is a PQ-to-PQ transition with a published roadmap and active testnet.

Coverage basis: PQ-native for ECC migration; documented PQ-to-PQ upgrade path

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: QRL 2.0 Testnet V2 is live as of March 2026. The migration process (snapshot, smart contract, user-initiated claim) is documented in draft form in community AMAs. Mainnet launch date is TBD pending audit completion.

Migration Mechanism, Governance & Ecosystem Coordination

Migration accessibility and defaults

Claim: PQ-native by design. All native account creation produces XMSS-based addresses by default. Wallet tooling (web, desktop, mobile, Ledger) supports only XMSS. No classical account creation path exists.

Coverage basis: PQ-native; PQ accounts are default and only option

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Multiple wallet platforms (web, desktop, mobile, Ledger hardware) all use XMSS exclusively. No fallback to classical key formats exists in any supported wallet.

Migration Mechanism, Governance & Ecosystem Coordination

Migration enforcement and coordination

Claim: PQ-native by design. The protocol enforces XMSS-only signatures. No vulnerable signing path exists to deprecate, freeze, or disable. No coordination needed to prevent unsafe fallback into classical systems.

Coverage basis: PQ-native; protocol-enforced XMSS-only; no vulnerable fallback exists

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Protocol-level enforcement is verifiable from source code. No bridge or wrapper contracts are active for the evaluated native scope.

Migration Mechanism, Governance & Ecosystem Coordination

Emergency disclosure, incident-response, or governance process for quantum-related vulnerabilities

Claim: QRL has published security contacts and has demonstrated responsiveness to external audit findings across multiple engagements. No formal quantum-specific incident-response playbook is publicly documented.

Coverage basis: General security process; no published quantum-specific IR playbook

Implementation score: 1 · Evidence confidence: Medium

Issue classification: assurance-only caveat · Score treatment: confidence-only

Assurance: QRL has security contacts (support@theqrl.org, press@theqrl.org) and has demonstrated responsive remediation of audit findings. The Halborn audit (2026) noted 'seamless' collaboration and that all findings were addressed. However, no formal quantum-specific incident-response playbook, vulnerability disclosure policy, or emergency governance process for cryptographic breaks is publicly documented. Per QRI Section 7.4, this is a note-only caveat because the absence of a formal playbook does not create a current quantum-vulnerable path. For PQ-native assets, lack of formal IR playbook should not reduce QRI Score per QRI Section 7.1.

The QRL Improvement Proposal (QIP) process and on-chain voting mechanism (developed 2021) provide governance infrastructure that could be leveraged for quantum-related decisions.

Algorithm & Implementation Assurance

Uses NIST-standardized, standards-track, or broadly reviewed PQC/hybrid-PQC algorithms

Claim: QRL mainnet uses XMSS, which is NIST-approved (NIST SP 800-208) and IETF-specified. The QRL 2.0 crypto library (qrypto.js) implements ML-DSA-87 (FIPS 204). Ephemeral messaging uses Dilithium and Kyber.

Coverage basis: NIST-standardized XMSS for all mainnet signatures; ML-DSA-87 in crypto library

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: XMSS was approved by NIST as a post-quantum signature standard (NIST SP 800-208). ML-DSA-87 (FIPS 204) is validated in the Halborn-audited qrypto.js library. Ephemeral messaging uses NIST round-3/standardized candidates.

XMSS (stateful hash-based) and ML-DSA-87 (lattice-based) are both NIST-approved post-quantum standards. No bespoke or weakly reviewed algorithms are used.

Algorithm & Implementation Assurance

Independent cryptographic and implementation audit

Claim: Three independent audits: Red4Sec (2018, 7 weeks, 67 findings), x41 D-Sec (2018, XMSS cryptography focus), Halborn (March 2026, qrypto.js library, 13 informational findings, zero cryptographic vulnerabilities).

Coverage basis: Multiple independent audits across codebase, cryptography, and library

Implementation score: 1 · Evidence confidence: High

Issue classification: assurance-only caveat · Score treatment: confidence-only

Assurance: Halborn (2026) is current for the qrypto.js library covering ML-DSA-87 and Dilithium5. Red4Sec and x41 D-Sec (2018) are stale but relevant for the mainnet XMSS implementation. The XMSS cryptographic design has not changed and is independently verifiable via NIST standardization. The Halborn audit found zero cryptographic vulnerabilities and included a 2.4M-input fuzzing campaign with zero false accepts. Per QRI Section 6.4: 'Stale but relevant audit of the same quantum-critical design: No QRI deduction by itself. Confidence normally capped at Medium unless other current review exists.' The current Halborn audit for the crypto library partially offsets the staleness of the 2018 audits, but the current mainnet node codebase has not undergone a recent end-to-end independent audit.

The Halborn audit scope covers the qrypto.js JavaScript library (ML-DSA-87/Dilithium5), which is intended for QRL 2.0, not the current Python-based QRL 1.x mainnet node directly. The 2018 audits covered the current mainnet codebase comprehensively but are 8 years old. The mainnet XMSS implementation is open-source and verifiable.

Algorithm & Implementation Assurance

Open-source, reproducible implementation

Claim: QRL core node, wallet, explorer, and cryptography libraries are all open-source under MIT License. Available on GitHub with active commit history. Latest release: v4.0.6 (March 2026).

Coverage basis: MIT-licensed open-source; public GitHub repositories

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: The QRL GitHub organization contains 80+ repositories. Core node repository has 30 contributors, 71 releases, and active maintenance (latest release v4.0.6, March 2026). The Halborn audit noted that build artifact reproducibility should be improved (committed dist files don't match fresh rebuild), but this is an informational finding that has been addressed.

Algorithm & Implementation Assurance

Parameter agility and future upgrade path

Claim: QRL's address format includes cryptographic descriptors enabling future algorithm upgrades. The QRL 2.0 roadmap includes ML-DSA-87 at launch with SPHINCS+ post-mainnet. XMSS tree height is configurable.

Coverage basis: Extensible address format documented; crypto-agile design

Implementation score: 1 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Extensible address format with cryptographic descriptors was implemented before mainnet launch. QRL 2.0 address format includes 3-byte cryptographic descriptors and 'Q' prefix. The project explicitly states 'Because the QRL 2.0 address model is inherently crypto-agile, SLH-DSA, and other future signature algorithms, can be seamlessly integrated after the network is live.'

Algorithm & Implementation Assurance

Stateful-signature safety

Claim: XMSS is a stateful signature scheme requiring OTS index tracking. QRL wallets track OTS state, display remaining signatures, and the block explorer shows OTS usage. Ledger hardware wallet integration provides hardware-level protection for signing state.

Coverage basis: Stateful XMSS with wallet-based OTS tracking; Ledger hardware support

Implementation score: 0.75 · Evidence confidence: High

Issue classification: operational/product caveat · Score treatment: score-reducing

Assurance: OTS index tracking is a known operational requirement for XMSS. QRL wallet tooling and block explorer provide OTS visualization. However, users can exhaust their OTS keys without creating a replacement, leading to permanent loss of signing capability for that address. This is not a quantum-attack vulnerability (quantum computers cannot exploit OTS statefulness to forge signatures) but it is an operational risk. QRL 2.0 plans to introduce stateless SPHINCS+ (SLH-DSA) to eliminate this concern.

Scored at 0.75 rather than 1.00 because XMSS statefulness creates a real operational risk of permanent fund lockup if OTS keys are exhausted without a replacement wallet. This is mitigated by wallet software and documentation, but the risk remains inherent to the stateful signature scheme. The QRI spec (Section 9.5) specifically calls out 'stateful-signature safety' including 'anti-reuse controls and signing-state discipline for XMSS/LMS-style schemes' as a scorable subfactor.

Algorithm & Implementation Assurance

Performance and resource-impact analysis

Claim: QRL documentation acknowledges XMSS transaction sizes (~3KB), longer key generation times, and larger signature sizes compared to ECDSA. The QRL GitHub README explicitly documents these characteristics.

Coverage basis: Documented performance characteristics; no independent formal benchmark

Implementation score: 1 · Evidence confidence: Medium

Issue classification: assurance-only caveat · Score treatment: confidence-only

Assurance: The GitHub README states: 'Hash-based signatures means larger transactions (3kb per tx, binary), longer keypair generation times and the need to record state of transactions.' No formal independent performance benchmark has been published. The network has been operating since 2018 with approximately 900 active nodes globally, demonstrating practical viability. Per QRI Section 7.4, lack of a formal performance benchmark is a note-only caveat unless resource constraints prevent safe use of the PQ path, which is not the case here.

Report metadata

Generation Details