papers/zoo-agent-nft/sections/04-agent-wallet-architecture.tex

\section{Agent Wallet Architecture}

\label{sec:wallet}

\subsection{Multi-Signature Design}

Each Agent NFT controls a dedicated wallet via multi-signature scheme:

\begin{figure}[t]
\centering
\begin{tikzpicture}[
    node distance=1.5cm,
    box/.style={rectangle, draw, minimum width=2cm, minimum height=0.8cm, align=center, fill=blue!10},
    wallet/.style={rectangle, draw, minimum width=2cm, minimum height=0.8cm, align=center, fill=green!10},
    key/.style={circle, draw, minimum size=0.6cm, fill=yellow!20}
]
    \node[box] (nft) {Agent NFT};
    \node[wallet, below=of nft] (wallet) {Agent Wallet};

    \node[key, below left=1cm and 1cm of wallet] (k1) {$K_A$};
    \node[key, below=1cm of wallet] (k2) {$K_O$};
    \node[key, below right=1cm and 1cm of wallet] (k3) {$K_R$};

    \draw[-] (nft) -- (wallet);
    \draw[-] (wallet) -- (k1) node[midway, left] {Agent};
    \draw[-] (wallet) -- (k2) node[midway, right] {Owner};
    \draw[-] (wallet) -- (k3) node[midway, right] {Recovery};

    \node[below=0.3cm of k1, font=\tiny] {2-of-3};
    \node[below=0.3cm of k2, font=\tiny] {threshold};
    \node[below=0.3cm of k3, font=\tiny] {signing};
\end{tikzpicture}
\caption{Agent wallet multi-signature architecture.}
\label{fig:wallet}
\end{figure}

\textbf{Key Roles}:
\begin{itemize}
    \item $K_A$: Agent key (controlled by AI reasoning engine)
    \item $K_O$: Owner key (controlled by NFT owner)
    \item $K_R$: Recovery key (optional, for emergency recovery)
\end{itemize}

\textbf{Signing Requirements}:
\begin{itemize}
    \item \textbf{Agent Actions} (within autonomy): $K_A$ alone
    \item \textbf{Owner Override}: $K_O$ alone
    \item \textbf{Autonomy Changes}: $K_A + K_O$
    \item \textbf{Emergency Recovery}: $K_O + K_R$
\end{itemize}

\subsection{Agent Key Management}

The agent key $K_A$ is generated and managed by the agent's \LLM{}:

\begin{algorithm}[t]
\caption{Agent Key Generation}
\label{alg:keygen}
\begin{algorithmic}[1]
\STATE \textbf{Input}: Agent model $M$, seed $s$
\STATE \textbf{Output}: Key pair $(sk_A, pk_A)$
\STATE $h \leftarrow \text{HKDF}(s, \text{Hash}(M))$
\STATE $(sk_A, pk_A) \leftarrow \text{KeyGen}(h)$
\STATE Store $sk_A$ in TEE or secure enclave
\RETURN $(sk_A, pk_A)$
\end{algorithmic}
\end{algorithm}

The private key is:
\begin{itemize}
    \item Derived deterministically from model hash (reproducible)
    \item Stored in trusted execution environment (TEE)
    \item Never exposed to the owner (owner cannot impersonate agent)
\end{itemize}

\subsection{Transaction Execution}

\begin{algorithm}[t]
\caption{Agent Transaction Execution}
\label{alg:tx}
\begin{algorithmic}[1]
\STATE \textbf{Input}: Agent $A$, action $a$
\STATE \textbf{Output}: Transaction result
\STATE \COMMENT{Autonomy check}
\IF{$a.\text{value} > A.\text{autonomy.maxTx}$}
    \STATE Require owner signature
\ENDIF
\IF{$a.\text{target} \notin A.\text{autonomy.whitelist}$}
    \STATE Require owner signature
\ENDIF
\STATE \COMMENT{Rate limiting}
\IF{$\text{now} - A.\text{lastTx} < A.\text{autonomy.cooldown}$}
    \RETURN Error: Cooldown
\ENDIF
\STATE \COMMENT{Execute}
\STATE $\sigma \leftarrow \text{Sign}(sk_A, a)$
\STATE Submit $(a, \sigma)$ to blockchain
\STATE Update $A.\text{lastTx} \leftarrow \text{now}$
\RETURN Success
\end{algorithmic}
\end{algorithm}