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zeekay
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Restructured from flat .tex/.pdf files into per-paper subdirectories. Added Antje Worring as co-author on all papers. Synced PDFs to pdfs/ for download site.
74 lines
2.9 KiB
TeX
74 lines
2.9 KiB
TeX
\section{Canonical Bridge Message Schema}
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\label{sec:messages}
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The message layer is frozen at this specification version. No additional message types may be introduced without a protocol upgrade.
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\subsection{Message Types}
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\begin{center}
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\begin{tabular}{@{}ll@{}}
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\toprule
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\textbf{Type} & \textbf{Semantics} \\
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\midrule
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\texttt{DEPOSIT\_V1} & Lock base asset; mint credit on destination \\
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\texttt{BURN\_V1} & Burn credit token on source chain \\
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\texttt{RELEASE\_V1} & Release base asset on destination chain \\
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\texttt{BACKING\_V1} & Backing attestation from vault oracle \\
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\bottomrule
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\end{tabular}
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\end{center}
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\subsection{Common Envelope}
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Every message \textsc{must} include the following 13 fields:
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\begin{center}
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\small
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\begin{tabular}{@{}lll@{}}
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\toprule
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\textbf{Field} & \textbf{Type} & \textbf{Description} \\
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\midrule
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\texttt{version} & \texttt{uint8} & Schema version \\
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\texttt{messageType} & \texttt{uint8} & Enum (4 types) \\
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\texttt{srcChainId} & \texttt{uint256} & Source chain \\
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\texttt{dstChainId} & \texttt{uint256} & Destination chain \\
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\texttt{routerAddress} & \texttt{address} & Sending router \\
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\texttt{assetId} & \texttt{bytes32} & Canonical asset ID \\
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\texttt{nonce} & \texttt{uint256} & Per-router sequence \\
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\texttt{amount} & \texttt{uint256} & Transfer amount (wei) \\
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\texttt{recipient} & \texttt{bytes32} & Destination address \\
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\texttt{expiry} & \texttt{uint256} & Expiration timestamp \\
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\texttt{originTxHash} & \texttt{bytes32} & Source event hash \\
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\texttt{payloadHash} & \texttt{bytes32} & Typed payload hash \\
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\texttt{domainSeparator} & \texttt{bytes32} & Deployment domain \\
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\bottomrule
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\end{tabular}
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\end{center}
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The \texttt{domainSeparator} is computed as:
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\begin{equation}
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\texttt{keccak256}\!\left(\texttt{abi.encode}\!\left(\mathcal{N},\; \mathcal{V},\; c,\; r\right)\right)
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\end{equation}
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where $\mathcal{N}$ is the protocol name, $\mathcal{V}$ the protocol version, $c$ the chain ID, and $r$ the router address. This closes five replay classes: chain replay, deployment replay, migration replay, same-signature context reuse, and duplicated source event processing.
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\subsection{Receive-Path Verification}
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\begin{requirement}[Minimum Verification Rules]
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\label{req:verify}
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Every receive path \textsc{must} verify all of the following before executing any state change:
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\begin{enumerate}[nosep]
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\item $\texttt{block.timestamp} \leq \texttt{expiry}$
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\item $\texttt{dstChainId} = \texttt{block.chainid}$
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\item $\texttt{routerAddress} = \texttt{address(this)}$
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\item $\texttt{nonce}$ unused for $(\texttt{srcChainId},\, \texttt{routerAddress},\, \texttt{assetId})$
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\item $\texttt{amount} > 0$
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\item $\texttt{recipient} \neq 0$
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\item $\texttt{assetId}$ recognized and enabled
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\item Message hash signed by $\geq t$ of $n$ authorized signers
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\end{enumerate}
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\end{requirement}
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