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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.
37 lines
1.6 KiB
TeX
37 lines
1.6 KiB
TeX
\section{What Is a Precompile}
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\subsection{The EVM Execution Model}
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The EVM executes smart contracts as sequences of opcodes (bytecodes). Each opcode has a
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fixed gas cost. Opcodes provide basic operations: arithmetic, memory access, storage,
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control flow. There are no opcodes for complex cryptographic operations like pairing
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checks or post-quantum signature verification.
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\subsection{Precompiles: Native Extensions}
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A precompile is a special contract address (typically in the range \texttt{0x0001}--\texttt{0x00ff}
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for Ethereum, \texttt{0x0200}--\texttt{0x02ff} for Lux extensions) where a \texttt{CALL}
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or \texttt{STATICCALL} invokes a native Go function instead of interpreting EVM bytecode.
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From Solidity's perspective, a precompile call looks like a normal external call:
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\begin{lstlisting}[language=Solidity,caption={Calling a precompile from Solidity}]
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// Call the BLS12-381 pairing precompile at 0x0200
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(bool success, bytes memory result) = address(0x0200).staticcall(
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abi.encodePacked(g1Point, g2Point)
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);
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require(success, "pairing check failed");
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bool pairingResult = abi.decode(result, (bool));
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\end{lstlisting}
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\subsection{Why Precompiles Instead of Libraries}
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Implementing BLS12-381 pairing in Solidity would cost approximately 50M gas (most of the
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block gas limit). The same operation as a precompile costs 113,000 gas---a 440x reduction.
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The reason: EVM opcodes have overhead per operation (gas metering, stack manipulation,
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memory management), and cryptographic operations require millions of field multiplications
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that incur this overhead for each one.
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%% ============================================================
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