papers/lux-quantum-threat-blockchain/sections/07-recommendations.tex

\section{Recommendations}

\label{sec:recommendations}

Based on our threat model, timeline analysis, and economic assessment, we make the
following concrete recommendations for blockchain protocol designers:

\subsection{Immediate Actions (2026)}

\begin{enumerate}[leftmargin=2em]
  \item \textbf{Deploy hybrid signatures}: Implement BLS + ML-DSA-65 dual signatures
        for validator consensus. ML-DSA signatures can be collected but not enforced
        initially to allow testing without consensus risk.
  \item \textbf{Deploy hybrid key exchange}: Implement X25519 + ML-KEM-768 for all
        node-to-node encrypted communication.
  \item \textbf{Register PQ public keys}: Require all validators to register ML-DSA
        public keys alongside BLS public keys. This enables enforcement without
        a second key generation ceremony.
  \item \textbf{Audit hash function usage}: Verify that all hash-based constructions
        (Merkle trees, address derivation) use $\geq$256-bit output hashes.
\end{enumerate}

\subsection{Medium-Term Actions (2027--2028)}

\begin{enumerate}[leftmargin=2em]
  \item \textbf{Enforce hybrid verification}: Require both BLS and ML-DSA signatures
        for epoch finality. Blocks that lack valid ML-DSA epoch proofs are not
        considered finalized.
  \item \textbf{Migrate bridge MPC}: Transition bridge threshold signature schemes
        from ECDSA-only to hybrid ECDSA + Pulsar (lattice-based threshold).
  \item \textbf{User-facing PQ signatures}: Enable EVM account abstraction with
        ML-DSA signature verification for user transactions.
\end{enumerate}

\subsection{Long-Term Actions (2029+)}

\begin{enumerate}[leftmargin=2em]
  \item \textbf{Monitor quantum progress}: Track CRQC development against the
        timeline estimates in Section~\ref{sec:timeline}.
  \item \textbf{Prepare for classical deprecation}: If quantum computers reach
        sufficient scale, deprecate BLS and ECDSA, retaining only post-quantum
        primitives.
  \item \textbf{Address hash migration}: If Grover-based collision attacks become
        practical, migrate Merkle tree hashes to 512-bit outputs.
\end{enumerate}

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