papers/hanzo-pq-crypto/sections/02-threat-model.tex

\section{Threat Model}

\label{sec:threat}
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\begin{definition}[Quantum Threat Timeline]
Let $T_Q$ be the year a CRQC capable of breaking 256-bit elliptic curve
cryptography becomes available. Let $T_D$ be the required data confidentiality
horizon. Data encrypted today is vulnerable if $T_D > T_Q$.
\end{definition}

Conservative estimates place $T_Q$ between 2030 and
2040~\cite{quantumtimeline}. For Hanzo infrastructure:
\begin{itemize}[leftmargin=1.1em]
    \item \textbf{Healthcare AI data}: $T_D = 50+$ years (HIPAA requirements).
    Migration urgency: \emph{critical}.
    \item \textbf{Financial AI data}: $T_D = 7$--$25$ years (regulatory
    retention). Migration urgency: \emph{high}.
    \item \textbf{Session tokens}: $T_D < 24$ hours (short-lived). Migration
    urgency: \emph{moderate} (but required for compliance).
    \item \textbf{Blockchain signatures}: $T_D = \infty$ (on-chain forever).
    Migration urgency: \emph{critical}.
\end{itemize}

\begin{theorem}[Migration Deadline]
For data with confidentiality horizon $T_D$ and migration timeline $T_M$
(years to complete migration), the latest safe migration start date is
$T_Q - T_M - T_D$. With $T_Q = 2033$ (median estimate), $T_M = 2$ years,
and $T_D = 10$ years: migration must begin by 2021. We are already in the
vulnerability window.
\end{theorem}

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