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A July commit removed eight papers on the premise "no license — DEX/non-custodial only". That premise is wrong: Lux operates an ATS, a broker-dealer, a transfer agent and a bank, and this material is resold at lux.financial. The merge that brought main in preserved the removal because the commit stated a reason, which is how a stale reason outlives the fact it rested on. Back, at the versions main carried — main never received the removal, so its copies are the later ones: the ATS architecture, the security-token standard, smart order routing, institutional custody, MPC custody, post-quantum securities, the SSB partnership and the CoinBridge brief. 83 files. Co-authored-by: Hanzo Dev <[email protected]>
65 lines
2.8 KiB
TeX
65 lines
2.8 KiB
TeX
\section{Hybrid Migration Path}
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\label{sec:hybrid}
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%% =====================================================================
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Immediate full migration to post-quantum signatures is impractical:
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existing wallets, hardware devices, and tooling use ECDSA. The Lux
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network implements a hybrid signature scheme for the transition period.
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\begin{definition}[Hybrid Signature]
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A hybrid signature on message $m$ is a pair
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$(\sigma_{\text{ECDSA}}, \sigma_{\text{ML-DSA}})$ where:
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\begin{itemize}[nosep]
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\item $\sigma_{\text{ECDSA}} = \mathsf{ECDSA.Sign}(sk_{\text{ECDSA}}, m)$
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\item $\sigma_{\text{ML-DSA}} = \mathsf{ML\text{-}DSA.Sign}(sk_{\text{ML-DSA}}, m)$
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\end{itemize}
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The chain accepts the transaction if \emph{either} signature verifies.
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\end{definition}
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\begin{theorem}[Hybrid Security: Best of Both Worlds]
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\label{thm:hybrid}
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The hybrid signature scheme is EUF-CMA secure as long as either
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ECDSA (under the ECDLP assumption) or ML-DSA (under the MLWE/MSIS
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assumptions) is EUF-CMA secure.
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\end{theorem}
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\begin{proof}
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Suppose an adversary $\mathcal{A}$ forges a hybrid signature
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$(\sigma^*_{\text{ECDSA}}, \sigma^*_{\text{ML-DSA}})$ on a new message
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$m^*$. For the forgery to be accepted, at least one of
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$\sigma^*_{\text{ECDSA}}$ or $\sigma^*_{\text{ML-DSA}}$ must verify.
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If $\sigma^*_{\text{ECDSA}}$ verifies, then $\mathcal{A}$ has forged an
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ECDSA signature, contradicting the ECDLP assumption. If
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$\sigma^*_{\text{ML-DSA}}$ verifies, then $\mathcal{A}$ has forged an
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ML-DSA signature, contradicting the MLWE/MSIS assumptions. Therefore,
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the forgery probability is at most
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$\epsilon_{\text{ECDSA}} + \epsilon_{\text{ML-DSA}}$, which is
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negligible as long as either $\epsilon_{\text{ECDSA}}$ or
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$\epsilon_{\text{ML-DSA}}$ is negligible.
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\end{proof}
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\subsection{Migration Phases}
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\begin{enumerate}[nosep]
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\item \textbf{Phase 0 (current).} Both classical and PQ precompiles
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are available. Transactions may use either. Most users
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continue with ECDSA.
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\item \textbf{Phase 1 (recommended).} Wallets begin generating
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hybrid key pairs (one ECDSA + one ML-DSA) and attaching hybrid
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signatures to transactions. Either signature is accepted.
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\item \textbf{Phase 2 (transition).} The chain begins requiring
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ML-DSA signatures on high-value operations (e.g., token
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issuance, validator registration). ECDSA remains valid for
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standard transfers.
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\item \textbf{Phase 3 (post-quantum).} When CRQCs are imminent or
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operational, the chain deprecates ECDSA-only transactions.
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Only ML-DSA or hybrid signatures are accepted.
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\end{enumerate}
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The key insight is that Phase~0 is already active: the precompiles
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exist at genesis. No hard fork is needed to enable post-quantum
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cryptography. The migration is purely a wallet-side upgrade.
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%% =====================================================================
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