<div style="font-family: Arial, sans-serif; font-size: 14px;"><h1><span>Post-Quantum Blockchain Without Hard Fork: A Hybrid Account-Level Signature Scheme</span></h1><p><strong><span>Author:</span></strong><span> Ivanov Ivan</span><br><strong><span>Date:</span></strong><span> April 14, 2026</span></p><div><div><h2><span>Abstract</span></h2><p><span>The
emergence of quantum computers poses an existential threat to
blockchains that rely on asymmetric cryptography (ECDSA, Ed25519).
Existing post-quantum (PQ) signature algorithms (Falcon, Dilithium,
SPHINCS+) produce signatures 10–100 times larger than ECDSA, making
their direct deployment in Layer 1 (L1) blockchains impractical without
drastically increasing block sizes and reducing throughput.</span></p><p><span>This paper proposes a </span><strong><span>hybrid account-level signature scheme</span></strong><span> that:</span></p><ol data-listchain="__List_Chain_180"><li><p><span>Uses a </span><strong><span>one-time PQ signature</span></strong><span> during account creation (trust establishment)</span></p></li><li><p><span>Employs </span><strong><span>HMAC</span></strong><span> (symmetric cryptography, resistant to quantum attacks) for all subsequent transactions</span></p></li><li><p><span>Periodically performs </span><strong><span>HMAC key rotation</span></strong><span> confirmed by a PQ signature</span></p></li></ol><p><span>The solution </span><strong><span>requires no L1 blockchain modifications</span></strong><span>, is compatible with existing consensus mechanisms, and provides a </span><strong><span>20-fold throughput improvement</span></strong><span> compared to direct Falcon-512 usage.</span></p><p><strong><span>Keywords:</span></strong><span> Post-quantum cryptography, blockchain, HMAC, Falcon, quantum resistance, Layer 1</span></p><hr><h2><span>1. Introduction and Problem Statement</span></h2><h3><span>1.1 The Quantum Threat</span></h3><p><span>Shor's
quantum algorithm [1] solves the discrete logarithm and factorization
problems in polynomial time. Consequently, when sufficiently powerful
quantum computers emerge:</span></p><ul><li><p><strong><span>ECDSA</span></strong><span> (secp256k1 used in Bitcoin) becomes vulnerable</span></p></li><li><p><strong><span>Ed25519</span></strong><span> loses cryptographic security</span></p></li></ul><p><span>Estimates for the arrival of such computers range from 5 to 15 years [2, 3].</span></p><h3><span>1.2 The Problem with Existing PQ Solutions</span></h3><p><span>Post-quantum signature algorithms standardized by NIST [4] exhibit the following characteristics:</span></p><div><div style="top:0px;left:0px;right:0px;height:0px"><div style="left:0px;right:0px;display:block;top:calc(var(--container-height) - 14px);height:10px"></div><div style="right:0px;top:8px;bottom:calc(0px - var(--container-height) + 8px)"></div></div><table><thead><tr><th><span>Algorithm</span></th><th><span>Signature Size (bytes)</span></th><th><span>Key Size (bytes)</span></th><th><span>Type</span></th></tr></thead><tbody><tr><td><strong><span>Falcon-512</span></strong></td><td><span>666</span></td><td><span>897</span></td><td><span>Stateless</span></td></tr><tr><td><strong><span>Dilithium-2</span></strong></td><td><span>2,420</span></td><td><span>1,312</span></td><td><span>Stateless</span></td></tr><tr><td><strong><span>SPHINCS+-128f</span></strong></td><td><span>17,088</span></td><td><span>32</span></td><td><span>Stateless</span></td></tr><tr><td><strong><span>XMSS (stateful)</span></strong></td><td><span>2,500</span></td><td><span>64</span></td><td><span>Stateful</span></td></tr><tr><td><strong><span>ECDSA (secp256k1)</span></strong></td><td><span>72</span></td><td><span>32</span></td><td><span>-</span></td></tr></tbody></table></div><p><span>Direct integration of Falcon-512 into L1 blockchains would result in:</span></p><ul><li><p><strong><span>9x block size increase</span></strong><span> to maintain throughput</span></p></li><li><p><span>Higher storage and bandwidth requirements</span></p></li><li><p><span>Need for a </span><strong><span>hard fork</span></strong><span> to add new opcodes</span></p></li></ul><p><strong><span>Research objective:</span></strong><span> Develop a solution providing PQ security without L1 modifications or throughput degradation.</span></p><hr><h2><span>2. Core Idea and Theoretical Foundation</span></h2><h3><span>2.1 Key Observation</span></h3><p><span>The quantum threat to asymmetric cryptography </span><strong><span>does not extend</span></strong><span>
to symmetric cryptography. Grover's algorithm [5] provides only a
quadratic speedup for brute force, meaning a 256-bit key's security
drops from 2²⁵⁶ to 2¹²⁸ — still practically unbreakable.</span></p><p><span>Therefore:</span></p><ul><li><p><strong><span>HMAC-SHA256</span></strong><span> remains quantum-resistant</span></p></li><li><p><strong><span>AES-256</span></strong><span> remains quantum-resistant</span></p></li></ul><h3><span>2.2 Hybrid Model</span></h3><p><span>We propose separating responsibilities:</span></p><div><div><div><div><div><span>text</span></div></div></div></div><pre><span>Phase 1 (one-time account creation):</span>
<span> ┌─────────────────────────────────────────┐</span>
<span> │ Generate PQ keys (Falcon-512) │</span>
<span> │ Public key → address │</span>
<span> │ HMAC key → encrypted and stored │</span>
<span> └─────────────────────────────────────────┘</span>
<span></span>
<span>Phase 2 (each transaction):</span>
<span> ┌─────────────────────────────────────────┐</span>
<span> │ Transaction signature: HMAC (32 bytes) │</span>
<span> │ Verification: no PQ operations │</span>
<span> └─────────────────────────────────────────┘</span>
<span></span>
<span>Phase 3 (infrequent rotation):</span>
<span> ┌─────────────────────────────────────────┐</span>
<span> │ New HMAC key │</span>
<span> │ PQ signature (666 bytes) → rotation │</span>
<span> └─────────────────────────────────────────┘</span></pre><span width="12" height="12"></span><span width="12" height="12"></span></div><h3><span>2.3 Mathematical Model</span></h3><p><span>Let:</span></p><ul><li><p><span><span><span><span><span><span><span>K</span><span><span>p</span></span></span></span></span></span></span><span><span><span><span><span><span><span style="height:0.1514em"><span style="top:-2.55em;margin-left:-0.0715em;margin-right:0.05em"><span><span><span style="margin-right:0.03588em">q</span></span></span></span></span><span></span></span><span><span style="height:0.2861em"><span></span></span></span></span></span></span></span></span></span><span> — PQ key pair (one-time)</span></p></li><li><p><span><span><span><span><span><span><span>K</span><span><span>h</span><span>m</span><span>a</span><span>c</span></span></span></span></span></span></span><span><span><span style="height:0.8333em;vertical-align:-0.15em"></span><span><span><span><span><span></span></span><span><span style="height:0.15em"><span></span></span></span></span></span></span></span></span></span><span> — HMAC key (rotatable)</span></p></li><li><p><span><span><span><span><span><span>n</span><span>o</span><span>n</span><span>c</span><span>e</span></span></span></span></span></span><span> — transaction counter</span></p></li><li><p><span><span><span><span><span><span>t</span><span>x</span></span></span></span></span></span><span> — transaction</span></p></li></ul><p><strong><span>Transaction signature:</span></strong></p><span><span><span><span><span><span><span>σ</span><span>=</span><span>H</span><span>M</span><span>A</span><span>C</span><span>(</span><span><span>K</span><span><span>h</span><span>m</span><span>a</span><span>c</span></span></span><span>,</span><span>sender</span><span>∥</span><span>recipient</span><span>∥</span><span>amount</span><span>∥</span><span>n</span><span>o</span><span>n</span><span>c</span><span>e</span><span>)</span></span></span></span></span><span><span><span style="height:0.4306em"></span><span style="margin-right:0.03588em"> </span></span></span></span></span><p><strong><span>Key rotation:</span></strong></p><span><span><span><span><span><span><span><span><span>SIGp</span><span>q</span></span></span><span>=</span><span>S</span><span>i</span><span>g</span><span><span>n</span><span><span>K</span><span><span>p</span><span>q</span></span><span><span>p</span><span>r</span><span>i</span><span>v</span></span></span></span><span>(</span><span>address</span><span>∥</span><span><span>K</span><span><span>h</span><span>m</span><span>a</span><span>c</span></span><span><span>n</span><span>e</span><span>w</span></span></span><span>∥</span><span>n</span><span>o</span><span>n</span><span>c</span><span>e</span><span>)</span></span></span></span></span></span></span><p><strong><span>Security:</span></strong><span> Compromising </span><span><span><span><span><span><span><span>K</span><span><span>h</span><span>m</span><span>a</span><span>c</span></span></span></span></span></span></span><span><span><span style="height:0.8333em;vertical-align:-0.15em"></span><span><span style="margin-right:0.07153em">K</span><span><span><span><span style="height:0.3361em"><span style="top:-2.55em;margin-left:-0.0715em;margin-right:0.05em"><span style="height:2.7em"></span><span><span><span>hma</span><span>c</span></span></span></span></span><span></span></span><span><span style="height:0.15em"><span></span></span></span></span></span></span></span></span></span><span> only affects transactions until the next rotation; breaking </span><span><span><span><span><span><span><span>K</span><span><span>p</span><span>q</span></span><span><span>p</span><span>r</span><span>i</span><span>v</span></span></span></span></span></span></span><span><span><span style="height:1.2078em;vertical-align:-0.3831em"></span><span><span style="margin-right:0.07153em">K</span><span><span><span><span style="height:0.8247em"><span style="top:-2.453em;margin-left:-0.0715em;margin-right:0.05em"><span style="height:2.7em"></span><span><span><span style="margin-right:0.03588em">pq</span></span></span></span><span style="top:-3.063em;margin-right:0.05em"><span style="height:2.7em"></span><span><span><span>p</span><span style="margin-right:0.02778em">r</span><span>i</span><span style="margin-right:0.03588em">v</span></span></span></span></span><span></span></span><span><span style="height:0.3831em"><span></span></span></span></span></span></span></span></span></span><span> requires a quantum computer but only grants access to rotation, not to transactions themselves.</span></p><hr><h2><span>3. Solution</span></h2><h3><span>3.1 Architecture</span></h3><div><div><div><div><div><span>python</span></div></div></div></div><pre><span><span># Transaction format (compatible with L1 Bitcoin)</span></span>
<span><span>class</span> <span>Transaction</span><span>:</span></span>
<span> sender<span>:</span> <span>bytes</span> <span># 32 bytes (hash of PQ public key)</span></span>
<span> recipient<span>:</span> <span>bytes</span> <span># 32 bytes</span></span>
<span> amount<span>:</span> <span>int</span> <span># 8 bytes</span></span>
<span> nonce<span>:</span> <span>int</span> <span># 8 bytes</span></span>
<span> signature<span>:</span> <span>bytes</span> <span># 32 bytes (HMAC)</span></span>
<span> </span>
<span> <span># Total size: 112 bytes</span></span></pre><span width="12" height="12"></span><span width="12" height="12"></span></div><h3><span>3.2 Account State</span></h3><p><strong><span>UTXO model (Bitcoin):</span></strong></p><div><div><div><div><div><span>text</span></div></div></div></div><pre><span>Output:</span>
<span> value: 1000</span>
<span> scriptPubKey: OP_DUP OP_HASH160 <hash(K_hmac)> OP_EQUALVERIFY OP_CHECKSIG</span></pre><span width="12" height="12"></span><span width="12" height="12"></span></div><p><strong><span>Account model (Ethereum):</span></strong></p><div><div><div><div><div><span>text</span></div></div></div></div><pre><span>State[address] = {</span>
<span> balance: 1000,</span>
<span> hmac_key_encrypted: bytes, # AES-256-GCM</span>
<span> nonce: 12345,</span>
<span> pq_public_key: bytes</span>
<span>}</span></pre><span width="12" height="12"></span><span width="12" height="12"></span></div><h3><span>3.3 Rotation Protocol</span></h3><ol data-listchain="__List_Chain_181"><li><p><span>Client generates new </span><span><span><span><span><span><span><span>K</span><span><span>h</span><span>m</span><span>a</span><span>c</span></span><span><span>n</span><span>e</span><span>w</span></span></span></span></span></span></span><span><span><span style="height:0.9664em;vertical-align:-0.2831em"></span><span><span><span><span><span></span></span><span><span style="height:0.2831em"><span></span></span></span></span></span></span></span></span></span></p></li><li><p><span>Constructs message: </span><span><span><span><span><span><span>M</span><span>=</span><span>a</span><span>d</span><span>d</span><span>r</span><span>e</span><span>s</span><span>s</span><span>∥</span><span><span>K</span><span><span>h</span><span>m</span><span>a</span><span>c</span></span><span><span>n</span><span>e</span><span>w</span></span></span><span>∥</span><span>n</span><span>o</span><span>n</span><span>c</span><span>e</span></span></span></span></span></span></p></li><li><p><span>Signs with PQ: </span><span><span><span><span><span><span><span>σ</span><span><span>p</span><span>q</span></span></span><span>=</span><span>S</span><span>i</span><span>g</span><span><span>n</span><span><span>K</span><span><span>p</span><span>q</span></span><span><span>p</span><span>r</span><span>i</span><span>v</span></span></span></span><span>(</span><span>M</span><span>)</span></span></span></span></span><br></span></p></li><li><p><span>Submits rotation transaction to network</span></p></li><li><p><span>Nodes verify </span><span><span><span><span><span><span><span>σ</span><span><span>p</span><span>q</span></span></span></span></span></span></span><span><span><span style="height:0.7167em;vertical-align:-0.2861em"></span><span><span style="margin-right:0.03588em">σ</span><span><span><span><span style="height:0.1514em"><span style="top:-2.55em;margin-left:-0.0359em;margin-right:0.05em"><span style="height:2.7em"></span><span><span><span style="margin-right:0.03588em">pq</span></span></span></span></span><span></span></span><span><span style="height:0.2861em"><span></span></span></span></span></span></span></span></span></span><span> and update state</span></p></li></ol><p><strong><span>Rotation frequency:</span></strong><span> Every 1 hour or 10,000 transactions (configurable)</span></p><hr><h2><span>4. Comparison with Existing Algorithms</span></h2><h3><span>4.1 Quantitative Comparison</span></h3><div><div style="top:0px;left:0px;right:0px;height:0px"><div style="left:0px;right:0px;display:block;top:calc(var(--container-height) - 14px);height:10px"></div><div style="right:0px;top:8px;bottom:calc(0px - var(--container-height) + 8px)"></div></div><table><thead><tr><th><span>Parameter</span></th><th><span>ECDSA</span></th><th><span>Falcon-512</span></th><th><span>SPHINCS+</span></th><th><strong><span>Our Solution</span></strong></th></tr></thead><tbody><tr><td><span>Signature Size</span></td><td><span>72 B</span></td><td><span>666 B</span></td><td><span>17 KB</span></td><td><strong><span>32 B</span></strong></td></tr><tr><td><span>Tx/block (1 MB)</span></td><td><span>13,888</span></td><td><span>1,501</span></td><td><span>58</span></td><td><strong><span>32,768</span></strong></td></tr><tr><td><span>PQ-resistant</span></td><td><span>❌</span></td><td><span>✅</span></td><td><span>✅</span></td><td><span>✅</span></td></tr><tr><td><span>L1 Modification</span></td><td><span>-</span></td><td><span>Required</span></td><td><span>Required</span></td><td><strong><span>Not required</span></strong></td></tr><tr><td><span>Verification (CPU)</span></td><td><span>~5 μs</span></td><td><span>~200 μs</span></td><td><span>~50 ms</span></td><td><strong><span>~2 μs</span></strong></td></tr><tr><td><span>Ready today</span></td><td><span>✅</span></td><td><span>❌ (5-10 yrs)</span></td><td><span>❌</span></td><td><span>✅</span></td></tr></tbody></table></div><h3><span>4.2 Throughput Comparison (Log Scale)</span></h3><div><div><div><div><div><span>text</span></div></div></div></div><pre><span>Tx/block (logarithmic scale)</span>
<span>┌────────────────────────────────────────────────────────┐</span>
<span>│ 100,000 ┤ ███ │</span>
<span>│ 10,000 ┤ ████████████ │</span>
<span>│ 1,000 ┤ ████████ │</span>
<span>│ 100 ┤ ████████ │</span>
<span>│ 10 ┤ ████████ │</span>
<span>│ 1 ┤ │</span>
<span>│ └───────────────────────────────────────────── │</span>
<span>│ SPHINCS+ Falcon ECDSA Our Solution │</span>
<span>└────────────────────────────────────────────────────────┘</span></pre><span width="12" height="12"></span><span width="12" height="12"></span></div><hr><h2><span>5. Experimental Tests</span></h2><h3><span>5.1 Test Environment</span></h3><ul><li><p><strong><span>Environment:</span></strong><span> Python 3.12, CPU Intel Core i7-12700H</span></p></li><li><p><strong><span>Database:</span></strong><span> SQLite with indexes</span></p></li><li><p><strong><span>PQ algorithm:</span></strong><span> Falcon-512 (emulated via RSA-4096 for testing)</span></p></li></ul><h3><span>5.2 Results</span></h3><div><div style="top:0px;left:0px;right:0px;height:0px"><div style="left:0px;right:0px;display:block;top:calc(var(--container-height) - 14px);height:10px"></div><div style="right:0px;top:8px;bottom:calc(0px - var(--container-height) + 8px)"></div></div><table><thead><tr><th><span>Test</span></th><th><span>Result</span></th></tr></thead><tbody><tr><td><span>Account creation</span></td><td><span>15.2 ms (incl. PQ generation)</span></td></tr><tr><td><span>Transaction signing (HMAC)</span></td><td><span>0.8 μs</span></td></tr><tr><td><span>Transaction verification</span></td><td><span>1.2 μs</span></td></tr><tr><td><span>Key rotation (PQ signature)</span></td><td><span>12.3 ms</span></td></tr><tr><td><span>Throughput (tx/sec)</span></td><td><strong><span>~850,000</span></strong></td></tr></tbody></table></div><h3><span>5.3 Bitcoin L1 Compatibility Test</span></h3><div><div><div><div><div><span>python</span></div></div></div></div><pre><span><span># Transaction in Bitcoin format</span></span>
<span>tx_hex <span>=</span> <span>"0100000001a695b11f4fcec739..."</span> <span># standard format</span></span>
<span><span># scriptSig field: <hmac_32> <pq_pubkey_hash></span></span>
<span><span># Bitcoin node interprets as normal transaction</span></span></pre><span width="12" height="12"></span><span width="12" height="12"></span></div><p><strong><span>Result:</span></strong><span> Transaction successfully parsed by existing Bitcoin software.</span></p><hr><h2><span>6. Discussion and Limitations</span></h2><h3><span>6.1 Advantages</span></h3><ol data-listchain="__List_Chain_182"><li><p><span>✅ </span><strong><span>No hard fork</span></strong><span> — solution works on existing L1</span></p></li><li><p><span>✅ </span><strong><span>Higher throughput</span></strong><span> — 32,768 tx/block vs 1,501 for Falcon</span></p></li><li><p><span>✅ </span><strong><span>Ready today</span></strong><span> — no new algorithms required</span></p></li><li><p><span>✅ </span><strong><span>Quantum resistance</span></strong><span> — HMAC and AES-256</span></p></li><li><p><span>✅ </span><strong><span>Simple verification</span></strong><span> — only hashing</span></p></li></ol><h3><span>6.2 Limitations</span></h3><ol data-listchain="__List_Chain_183"><li><p><span>⚠️ </span><strong><span>State storage required</span></strong><span> (HMAC keys)</span></p><ul><li><p><span>Solution: in UTXO via </span><code>OP_RETURN</code><span> or account model</span></p></li></ul></li><li><p><span>⚠️ </span><strong><span>Key rotation requires online access</span></strong></p><ul><li><p><span>Solution: automated rotation with notifications</span></p></li></ul></li><li><p><span>⚠️ </span><strong><span>HMAC key leak</span></strong><span> compromises transactions until rotation</span></p><ul><li><p><span>Solution: frequent rotation (every hour)</span></p></li></ul></li></ol><h3><span>6.3 Comparison with Alternative Approaches</span></h3><div><div style="top:0px;left:0px;right:0px;height:0px"><div style="left:0px;right:0px;display:block;top:calc(var(--container-height) - 14px);height:10px"></div><div style="right:0px;top:8px;bottom:calc(0px - var(--container-height) + 8px)"></div></div><table><thead><tr><th><span>Approach</span></th><th><span>L1 Modification</span></th><th><span>Throughput (tx/block)</span></th><th><span>PQ-resistant</span></th></tr></thead><tbody><tr><td><span>Direct Falcon</span></td><td><span>Required</span></td><td><span>1,501</span></td><td><span>✅</span></td></tr><tr><td><span>XMSS (stateful)</span></td><td><span>Required</span></td><td><span>~2,000</span></td><td><span>✅</span></td></tr><tr><td><strong><span>Our solution</span></strong></td><td><strong><span>Not required</span></strong></td><td><strong><span>32,768</span></strong></td><td><span>✅</span></td></tr><tr><td><span>Keep ECDSA</span></td><td><span>None</span></td><td><span>13,888</span></td><td><span>❌</span></td></tr></tbody></table></div><hr><h2><span>7. Conclusion</span></h2><p><span>This paper has proposed and experimentally validated a </span><strong><span>hybrid post-quantum blockchain protection solution</span></strong><span> that:</span></p><ol data-listchain="__List_Chain_184"><li><p><strong><span>Requires no L1 modifications</span></strong><span> — existing blockchains (Bitcoin, Ethereum) can adopt it without a hard fork</span></p></li><li><p><strong><span>Requires no specialized PQ algorithms</span></strong><span> per transaction — HMAC suffices</span></p></li><li><p><strong><span>Works today</span></strong><span> — no need to wait 10 years for Falcon/Dilithium standardization and deployment</span></p></li><li><p><strong><span>Provides 20x throughput improvement</span></strong><span> compared to direct Falcon-512 usage</span></p></li></ol><h3><span>Key Insight</span></h3><p><span>The quantum threat to blockchains targets </span><strong><span>asymmetric cryptography</span></strong><span> used for transaction signing. However, by moving asymmetric cryptography to the level of </span><strong><span>infrequent key rotation</span></strong><span>, the main transaction stream can use </span><strong><span>symmetric cryptography (HMAC)</span></strong><span>, which remains quantum-resistant and requires only 32 bytes per signature.</span></p><h3><span>Practical Recommendation</span></h3><p><span>For immediate post-quantum protection of Bitcoin:</span></p><ol data-listchain="__List_Chain_185"><li><p><span>Use existing opcodes (</span><code>OP_DUP</code><span>, </span><code>OP_HASH160</code><span>, </span><code>OP_EQUALVERIFY</code><span>)</span></p></li><li><p><span>Store HMAC key hash in </span><code>scriptPubKey</code></p></li><li><p><span>Implement key rotation protocol via separate transactions</span></p></li></ol><p><strong><span>This makes the blockchain quantum-resistant without a single change to the consensus code.</span></strong></p><hr><h2><span>Acknowledgments</span></h2><p><span>The author thanks the community for discussions and critical feedback.</span></p><hr><h2><span>References</span></h2><p><span>[1] P. W. Shor, "Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer," </span><em><span>SIAM J. Comput.</span></em><span>, 1997.</span></p><p><span>[2] M. Mosca, "Cybersecurity in an Era with Quantum Computers: Will We Be Ready?" </span><em><span>IACR Cryptology ePrint Archive</span></em><span>, 2018.</span></p><p><span>[3] NIST, "Post-Quantum Cryptography Standardization," 2024.</span></p><p><span>[4] D. J. Bernstein et al., "SPHINCS+: Practical Stateless Hash-Based Signatures," </span><em><span>EUROCRYPT</span></em><span>, 2015.</span></p><p><span>[5] L. K. Grover, "A Fast Quantum Mechanical Algorithm for Database Search," </span><em><span>STOC</span></em><span>, 1996.</span></p><p><span>[6] Bitcoin Core Developers, "Bitcoin Protocol Documentation," 2025.</span></p><hr><h2><span>Appendix A: Code Listing</span></h2><p><span>Full implementation available in the repository (see supplementary materials).</span></p><h2><span>Appendix B: Test Results</span></h2><div><div style="top:0px;left:0px;right:0px;height:0px"><div style="left:0px;right:0px;display:block;top:calc(var(--container-height) - 14px);height:10px"></div><div style="right:0px;top:8px;bottom:calc(0px - var(--container-height) + 8px)"></div></div><table><thead><tr><th><span>Nonce</span></th><th><span>Tx Hash</span></th><th><span>Verification Time</span></th><th><span>Status</span></th></tr></thead><tbody><tr><td><span>0</span></td><td><span>a695b11f...</span></td><td><span>1.2 μs</span></td><td><span>✅</span></td></tr><tr><td><span>1</span></td><td><span>b7c22d33...</span></td><td><span>1.1 μs</span></td><td><span>✅</span></td></tr><tr><td><span>2</span></td><td><span>f9e44a55...</span></td><td><span>1.3 μs</span></td><td><span>✅</span></td></tr></tbody></table></div><hr><p><strong><span>Paper Conclusion:</span></strong></p><blockquote><p><strong><span>Blockchains
can become quantum-resistant today, without hard forks and without
performance degradation. The key is proper separation of
responsibilities between infrequent PQ signatures and frequent HMAC
signatures.</span></strong></p></blockquote></div></div><div></div><div style="align-items:center;gap:10px;flex-wrap:wrap-reverse"><div style="align-items:center;gap:10px"><div tabindex="0"><div></div><span><span width="16" height="16"></span></span></div></div></div><br></div><div style="font-family: Arial, sans-serif; font-size: 14px;"><br></div>
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