Quantum security has moved from theoretical risk to an active engineering priority for Layer‑1 blockchains as projects and public bodies plan migrations to post‑quantum cryptography (PQC). The shift is driven by the “harvest now, decrypt later” threat and projections that practical quantum attacks could become feasible between 2030 and 2040; networks are testing lattice‑ and hash‑based signatures and key‑encapsulation schemes to protect transaction finality and historical state.
Shor’s algorithm can efficiently factor large integers and solve discrete logarithms, threatening modern public‑key signatures; Grover’s algorithm speeds brute‑force against symmetric keys and hashes, effectively halving bit‑security. Post‑Quantum Cryptography (PQC) is a family of classical‑software algorithms designed to resist both classical and quantum attacks.
NIST standardization has accelerated adoption by naming lattice‑ and hash‑based schemes—examples cited include CRYSTALS‑Kyber for KEM (ML‑KEM), CRYSTALS‑Dilithium for signatures (ML‑DSA), and SPHINCS+ (SLH‑DSA) as a conservative fallback.
The practical cost of migration is material. Current ECDSA signatures average 64 bytes; ML‑DSA signatures can reach ~2.420 bytes and hash‑based SLH‑DSA signatures range from 8 KB to 50 KB. ML‑KEM key material can expand to 800–4.600 bytes. Those larger keys and signatures increase transaction size, bandwidth and on‑chain storage, raising gas costs and pressuring throughput (TPS) and Layer‑2 aggregation schemes. Developers are therefore evaluating trade‑offs between cryptographic resilience and network performance, with many experiments confined to testnets and Layer‑2 pilots.
Which networks and approaches are preparing first for quantum security
Networks and vendors are taking varied routes: built‑in post‑quantum designs, retrofits, and hybrid wrappers. The Quantum Resistant Ledger (QRL) was built with hash‑based XMSS from inception, avoiding retrofit complexity. Algorand has adopted FALCON signatures and signs State Proofs with post‑quantum schemes, and it is publicly positioning further PQC work in its roadmap; pilots for ML‑DSA in smart contracts are expected in 2025.
QANplatform, Cellframe and Quranium are presented as Layer‑1s with native or audited quantum‑resistant protocols; Quranium has reported institutional investment that underscores its focus on PQC and AI integration.
Large incumbent chains are pursuing hybrid strategies to limit disruption. Ethereum and Bitcoin are exploring phased migrations using Layer‑2 testing with zkEVM and STARK proofs, and protocol upgrades (for example Verkle trees and execution‑layer hooks) to enable gradual PQC adoption without a hard fork rewrite. Commercial “Quantum Crypto Wrapper” (QCW) solutions are emerging to layer PQC protections over existing chains and dApps, enabling retrofitting without rebuilding core protocols. Public‑private initiatives also surfaced, including a plan to design a sovereign quantum‑resistant blockchain for Abu Dhabi with Agile Dynamics and contributions from teams such as SEALCOIN.
The ecosystem is moving from awareness to engineering: early adopters favor native PQC or audited hybrid designs, while major networks test PQC on Layer‑2 before mainnet changes.
