Scalable Quantum-Resistant Blockchain Architecture

• Scalable quantum-resistant blockchain architecture is defined by its fusion of classical ledger systems with post-quantum and quantum communication methods to safeguard against quantum adversaries.
• It employs modular decoupling, small validator committees, and off-chain storage to enhance throughput, reduce latency, and limit on-chain data growth.
• The design leverages quantum-safe protocols such as QKD, lattice-based cryptography, and quantum digital signatures to ensure robust cross-chain interoperability and consensus.

Scalable quantum-resistant blockchain architecture denotes a family of ledger and interoperability designs that preserve security against quantum-capable adversaries while maintaining usable throughput, latency, and system size. The literature distinguishes post-quantum blockchains, which remain classical in data structure and networking but replace vulnerable cryptographic components with post-quantum primitives, from quantum blockchains, which use quantum information mechanisms such as QKD, entanglement, and quantum digital signatures for authentication, chaining, or consensus (Ghosh, 18 Jul 2025). Across both directions, scalability is pursued by modular layering, small validator committees, off-chain storage with on-chain commitments, batched verification, sharded coordination, and, in quantum-secured consortium settings, star-topology key-distribution networks rather than all-to-all quantum links (Li et al., 16 Mar 2026).

1. Architectural scope and system models

A central distinction in the literature is between architectures that harden existing blockchains and architectures that redefine the ledger around quantum communication. In the first class, the blockchain remains a classical replicated state machine, but its signature, key-exchange, and sometimes hashing layers are replaced or augmented with post-quantum cryptography. In the second class, integrity and authentication are derived from quantum mechanical principles such as no-cloning, measurement disturbance, monogamy of entanglement, time-entanglement, or quantum key distribution (Ghosh, 18 Jul 2025).

Within post-quantum classical designs, the architecture is often explicitly layered. QLink is a Layer‑3 interoperability protocol that sits above existing Layer‑1 blockchains and Layer‑2 scaling solutions and provides a quantum‑safe, decentralized bridge layer for cross‑chain messaging and asset transfers. Its design does not redefine the underlying ledgers; instead it introduces a separate interoperability layer whose validators communicate over QKD‑secured channels, use NIST‑standard post‑quantum signatures, and keep private keys sealed in hardware security modules (Silva et al., 20 Dec 2025). The same paper also sketches an end-to-end architecture in which L1 uses PQC-secured consensus and transaction signing, L2 uses quantum-safe rollups or channels, and L3 uses QLink for interoperability.

A second recurrent pattern is the separation of large application data from ledger commitments. The file-transfer architecture in "Development of a Quantum-Resistant File Transfer System with Blockchain Audit Trail" stores files off-chain while logging compact metadata on an immutable blockchain ledger. The workflow separates Sender, User Storage and Blockchain, and Requestor modules, with the blockchain recording {sender_id, file_name, timestamp, status} rather than bulk content (Sola-Thomas et al., 10 Apr 2025). A related but more radical design move appears in the hash-based commit–reveal alternative, where authorization is encoded as two lightweight transactions carrying fixed-size hash outputs rather than a single transaction carrying a large post-quantum signature. This redesign treats transaction semantics, not only signature replacement, as the primary architectural lever for scalability (Finlow-Bates et al., 7 May 2026).

2. Security foundations and cryptographic substrate

The threat model is dominated by Shor’s and Grover’s algorithms. Shor’s algorithm breaks RSA, ECDSA, ECDH, EdDSA, and related public-key systems, while Grover’s algorithm quadratically accelerates brute-force search against hashes and symmetric primitives. The survey literature therefore treats any architecture that continues to rely on ECDSA, EdDSA, ECDH, or RSA as non-quantum-resistant at the core signature and key-agreement layers, and it recommends longer-output hash functions or revised security margins for hash-based components (Fernandez-Carames et al., 2024).

Within post-quantum classical architectures, the dominant cryptographic building blocks are lattice-based and hash-based primitives. QLink assigns each validator a PQC keypair $(pk_i, sk_i)$ generated by a NIST-standard PQC signature scheme, primarily CRYSTALS‑Dilithium (ML‑DSA) and optionally Falcon or SPHINCS+, and defines a quorum proof as

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$

with the Byzantine threshold

$T = 2f + 1 \quad \text{for} \quad n = 3f+1.$

For lattice-based schemes such as Dilithium and Falcon, the underlying hardness assumption is Learning With Errors (LWE), written in simplified form as

$b = A s + e \mod q,$

where recovering $s$ from random $A$ and noisy $b$ is assumed computationally hard for both classical and quantum algorithms at appropriate parameter sizes (Silva et al., 20 Dec 2025).

Practical PQ signature integration has also been benchmarked directly. PQS‑BFL uses ML‑DSA‑65 and reports average PQC sign time: 0.65 ms, verify time: 0.53 ms with a fixed signature size of 3309 Bytes, while storing only payload hashes on-chain and verifying signatures in smart-contract logic (Commey et al., 3 May 2025). The file-transfer architecture adopts CRYSTALS‑Kyber for encryption or key establishment and CRYSTALS‑Dilithium for digital signatures, with off-chain file protection and on-chain audit records (Sola-Thomas et al., 10 Apr 2025).

QKD-based architectures add an information-theoretic layer beneath these post-quantum mechanisms. In QLink, validators establish symmetric session keys through QKD and require

$$R_{ij} = R_0 \cdot e^{-\lambda d_{ij}}, \qquad R_{ij} > B_{ij},$$

so that key generation outpaces validator traffic and allows true one‑time pad (OTP) usage for validator messages. Those keys are used for OTP encryption and VMAC authentication, while the validators’ PQC private keys remain in HSM enclaves, where Sign(sk_i, m) is the only exposed operation (Silva et al., 20 Dec 2025).

Quantum-native designs move beyond computational assumptions altogether. The high-dimensional time-entanglement protocol explicitly replaces hash and signature complexity assumptions with the no‑cloning theorem, measurement‑disturbance, monogamy of entanglement, and high‑dimensional Bell correlations across time. The generalized Gram–Schmidt blockchain similarly grounds security in no-cloning, Heisenberg uncertainty, and the ordered dependence of each lifted block state on the entire prefix of prior block encodings (Aktaş et al., 23 Dec 2025).

3. Consensus, authentication, and interoperability

In layered post-quantum interoperability architectures, consensus is typically classical BFT protected by quantum-safe authentication. QLink models the protocol as

$$\text{QLink} = \text{PQC}(\text{HSM}, \text{Algo}) + \text{QKD}(R(d)) + V(T) + C(\text{BFT}),$$

with the operational conditions $R(d) > B$ and $\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$0. Each validator contains a PQC/HSM module, a QKD interface, a consensus engine, chain light‑clients / SPV, and bridge logic (Silva et al., 20 Dec 2025).

Its cross-chain protocol is a strict validation-and-quorum pipeline. A user locks assets in a bridge contract on chain A; validators observe the event via SPV or light-client proofs; each validator checks proof validity and confirmation depth; a leader proposes a bundle containing event description $\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$1 and proof data over QKD‑derived OTP+VMAC channels; validators use HSMs to compute

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$2

and once $\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$3, the aggregated proof

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$4

is submitted to chain B, whose bridge contract verifies signatures, registered validator keys, and quorum before minting or releasing assets (Silva et al., 20 Dec 2025).

A distinct consensus line replaces classical signatures entirely with quantum digital signatures. The circular QBA protocol is built from One‑Time Universal Hashing Quantum Digital Signature (OTUH‑QDS) instances with roles signer, forwarder, and verifier, where the verifier is always a Certificate Authority (CA). Its distribution phase uses correlated keys satisfying

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$5

and its signature rate is

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$6

The resulting QBA communication complexity is

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$7

with a star-shaped quantum network using exactly $\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$8 quantum links and a fault-tolerance requirement

$\Pi = \{ \sigma_i : i \in I,\ |I| \ge T \},$9

This combination is presented as a scalable framework for large-scale QBA networks and a basis for a practical quantum blockchain (Weng et al., 12 Feb 2026).

A consortium-specific alternative uses QKD-derived symmetric authentication rather than either classical signatures or quantum digital signatures. The TF‑QKD architecture introduces Evidence Keys $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$0 for transaction authentication and Consensus Keys $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$1 for BFT messages. Messages are authenticated by Wegman‑Carter MAC vectors; for node $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$2 and recipient $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$3,

$T = 2f + 1 \quad \text{for} \quad n = 3f+1.$4

and the system finalizes blocks by BFT voting under $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$5. Evidence keys are later disclosed for public audit, whereas consensus keys are never disclosed and are securely erased after use (Li et al., 16 Mar 2026).

4. Scalability mechanisms and cost models

The most direct scalability mechanism in the literature is modular decoupling. QLink’s separate Layer‑3 matters because it avoids modifying every L1/L2, isolates bridge logic and validator communication in a specialized layer, and reduces interoperability complexity from “N² bridges” to “N to L3”. It also constrains the consensus domain to small validator committees of 21–31 validators, requiring only $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$6 signatures per cross-chain proof, with communication complexity $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$7 or $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$8 depending on the BFT variant (Silva et al., 20 Dec 2025).

The same work reports concrete overhead measurements showing that the quantum-safe mechanisms are not the dominant latency term. For validator traffic $T = 2f + 1 \quad \text{for} \quad n = 3f+1.$9, the QKD simulations give: 5 km with $b = A s + e \mod q,$0 and ~707× key surplus, 10 km with $b = A s + e \mod q,$1 and ~550× surplus, and 50 km with $b = A s + e \mod q,$2 and ~62× surplus. Packet loss stays <0.1% at all distances, PQC signing in HSM is <10 ms per validator, proof size rises from ~1 KB (ECDSA) to ~3–6 KB (PQC), and total QLink overhead for a Bitcoin→Ethereum bridge is <1 second, versus ~60 minutes for Bitcoin confirmation and ~13 minutes for Ethereum confirmation (Silva et al., 20 Dec 2025).

For consortium chains that rely on QKD rather than public-key signatures, the decisive scalability result is physical-network complexity. Conventional BB84-style integration needs

$b = A s + e \mod q,$3

optical links, whereas the TF‑QKD star requires

$b = A s + e \mod q,$4

For $b = A s + e \mod q,$5, the number of required fibers drops by ~98%. The same architecture defines key demand as

$b = A s + e \mod q,$6

and requires

$b = A s + e \mod q,$7

Under the reported parameters, a 50 km, 20-node deployment with $b = A s + e \mod q,$8 and $b = A s + e \mod q,$9 supports peak throughput of 303 TPS, while smaller or lower-throughput networks extend to inter-city distances (Li et al., 16 Mar 2026).

Other architectures attack scalability primarily through data placement and transaction semantics. The file-transfer architecture stores actual file contents off-chain and logs only compact metadata on-chain; for a 2 GB file, In‑Memory PQC takes about 1.3 seconds, AES about 1.2 seconds, and File‑Based PQC about 3.8 seconds, while the file-based mode has “constant to zero RAM utilization” (Sola-Thomas et al., 10 Apr 2025). PQS‑BFL applies the same principle to model updates: clients sign only the hash

$s$0

and the smart contract stores verified commitments rather than payloads. In that setting, gas usage per update averages $s$1 units for PQC configurations, average transaction times are around 4.8 s, and the cryptographic overhead relative to transaction time remains minimal (around 0.01–0.02% for PQC with blockchain) (Commey et al., 3 May 2025).

A more aggressive optimization discards PQ signatures from the transaction envelope entirely. The hash-based commit–reveal construction replaces a single signature-bearing transaction with two lightweight transactions carrying fixed-size (32-byte) hash output values derived from SHA‑256, BLAKE, or Keccak. The effective transaction footprint rises by only approximately 1.5× to 2× per authorization event, in contrast to the 50×–100× system-wide cost amplification projected for direct insertion of large PQ signatures such as 2–4.5 KB Dilithium or 10–30 KB SPHINCS+ signatures (Finlow-Bates et al., 7 May 2026).

5. Quantum-native blockchain constructions

Quantum-native architectures attempt to make blockchain integrity a property of quantum state evolution rather than a property of computational hardness. In the high-dimensional time-entanglement protocol, each block carries classical data, high-dimensional time-entangled Bell states, and classical metadata such as time indices, measurement outcomes, and derived keys. A standard high-dimensional Bell state is

$s$2

and its time-entangled version is written as

$s$3

Intermediate blocks perform high-dimensional Bell-state measurements (HDBM), derive private keys from the Bell outcomes, and publish public keys as modulo-$s$4 sums. Validation is based on XOR conditions over public-key components rather than hash pointers, and scalability follows from high-dimensional superdense coding, which carries up to $s$5 bits per entangled pair and reduces the number of physical qudits required per block (Aktaş et al., 23 Dec 2025).

A second fully quantum line uses dimensional lifting generalized Gram–Schmidt procedure. Transactions are encoded into multi-qubit states $s$6, aggregated into preliminary block vectors $s$7, and lifted from $s$8 into $s$9, where the orthogonalized block states $A$0 satisfy

$A$1

for a partial isometry $A$2. The chain property arises because each $A$3 depends on the ordered list of all previous block encodings, a feature described as the non‑democratic nature of generalized Gram–Schmidt. Security is then derived from the fact that altering any $A$4 changes all later $A$5, while node-specific encryption of the lifted dimensions places part of each block in an unknown basis protected by the no-cloning theorem (Nilesh et al., 2021).

Time-entangled GHZ designs provide a third quantum-native construction. The protocol with phase encoding begins from temporal Bell states and fuses them into a temporal GHZ chain in which each block contributes both a 2-bit string and a phase $A$6 encoding the rest of the classical block. Its global chain state accumulates the phase

$A$7

so that any data or timing modification changes the expected GHZ measurement basis. The architecture uses two qubits per block, giving constant qubit cost per block while retaining time-entangled immutability. The paper, however, also states that the proposal is entirely conceptual and does not account for practical implications such as noise, decoherence, state preparation errors, or fault tolerance (Konara et al., 20 Jul 2025).

Quantum money yields a different scalability mechanism. The hybrid payment architecture built from quantum lightning and a classical blockchain uses smart contracts only to lock coins to banknote serial numbers, recover lost notes, and redeem value. Ordinary payments occur by direct transfer of the quantum state and local verification, so “transactions are not recorded on the blockchain” and “the throughput is unbounded”; payments are “as quick as quantum communication, regardless of the total number of users” (Coladangelo et al., 2020). This does not redefine the ledger as a quantum state, but it does relocate the dominant payment path off-chain through non-clonable quantum banknotes.

6. Deployment constraints, migration, and research frontiers

The near-term architectural center of gravity remains post-quantum classical blockchains rather than fully quantum ledgers. The survey literature states that post-quantum blockchains are more deployment-ready, whereas quantum blockchains remain “mostly theoretical” and are limited by quantum hardware, entanglement distribution, quantum memories, and routing overhead. The same surveys recommend modular cryptographic interfaces, dual-signature transition periods, longer hash outputs, layer‑2 mechanisms, sharding, batching, stateless clients, and explicit migration of exposed classical public keys before large-scale quantum computers become operational (Ghosh, 18 Jul 2025).

QLink’s own limitations are concrete. It currently targets committees of 21–31 validators; scaling to hundreds “requires more efficient aggregation and QKD scheduling.” Fiber QKD is “limited by distance and requires specialized infrastructure,” satellite QKD is “still maturing,” and “efficient on‑chain PQC verification remains an area of active engineering” (Silva et al., 20 Dec 2025). The TF‑QKD consortium design identifies a different bottleneck: even though the quantum physical layer scales from $A$8 to $A$9, the logical BFT layer still requires $b$0 authenticated messages, and deployability depends on phase stabilization, synchronization, detector cost, and finite-size effects not captured by asymptotic formulas (Li et al., 16 Mar 2026).

Broader blockchain infrastructure research pushes the architecture outward into sharded and interoperable data economies. The tutorial on intelligent cyber–physical–social systems places BrokerChain and GriDB at the scalability layer, where cross-shard operations are offloaded to brokers or delegates and on-chain logic verifies only succinct proofs over authenticated data structures. It couples this with crypto‑agility, algorithm identifiers for hybrid signatures, and on-chain anchoring of Croissant metadata for dataset provenance (Guo et al., 5 Jun 2026). This suggests that scalable quantum-resistant architecture is increasingly understood not only as a base-layer cryptographic migration, but as a coordination stack linking PQ-secured consensus, succinct cross-domain verification, and long-lived provenance for data-centric systems.

The persistent controversy is therefore not whether quantum threats matter, but where the architectural burden should fall. One line minimizes change at the ledger level and treats post-quantum migration as a problem of cryptographic substitution, with careful control of signature size, verification cost, and on-chain data growth. A second line redesigns transaction semantics, as in commit–reveal or off-chain commitment architectures, to avoid carrying large PQ artifacts at all. A third line seeks information-theoretic protection through QKD, quantum digital signatures, or entanglement-based chaining, accepting tighter deployment constraints in exchange for stronger security claims. Current work does not collapse these lines into a single canonical design. Instead, it presents a spectrum of architectures whose common objective is to preserve authenticity, integrity, interoperability, and throughput when classical public-key assumptions are no longer reliable.