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Abstract

EVM precompile wrappers for BN254 (alt_bn128) operations: ECADD (0x06), ECMUL (0x07), ECPAIRING (0x08). Wraps LP-146 BN254 first-party body with EIP-196/197 ABI encoding + gas accounting. Hot-path on Lux C-Chain for ZK rollup verifiers and identity proofs. First-party Go + C++ CPU + Metal/CUDA/WGSL GPU.

Specification

Parameters

• Precompile addresses: 0x06 (ECADD), 0x07 (ECMUL), 0x08 (ECPAIRING)
• Input ABI: 32-byte big-endian field elements per EIP-196 §"Specification"
• Pairing input: tuples of (G1, G2), k = 1..16 typical; cost grows linearly
• Gas: EIP-196 (Byzantium) revised by EIP-1108 (Istanbul) — ECADD 150, ECMUL 6000, ECPAIRING 45000+34000·k

Algorithm

• ECADD: validate G1 points on curve + in subgroup, then R = P + Q
• ECMUL: scalar mul with constant-time NAF
• ECPAIRING: product-of-pairings Π e(P_i, Q_i) checked against 1 ∈ Fp12

KAT

• EIP-196/197 reference vectors (Ethereum testsuite) PASS
• lux/crypto/evm256/test/kat.json — 36 vectors, byte-equal go-ethereum

Implementation

Go canonical

• lux/crypto/evm256/{ecadd,ecmul,ecpairing}.go — first-party, wraps LP-146 BN254
• Module: github.com/luxfi/crypto/evm256 @ v1.18.3

C++ CPU canonical

• luxcpp/crypto/evm256/cpp/{ecadd,ecmul,ecpairing}.{hpp,cpp} (uses libbn254.a from LP-146)
• C-ABI: luxcpp/crypto/evm256/c-abi/evm256_capi.h
• Library: libevm256.a

GPU kernels

• Metal: luxcpp/crypto/evm256/gpu/metal/evm256.metal — batch ECADD/ECMUL/ECPAIRING for ZK-rollup batch verification
• CUDA: luxcpp/crypto/evm256/gpu/cuda/evm256.cu
• WGSL: luxcpp/crypto/evm256/gpu/wgsl/evm256.wgsl

Determinism

• CPU↔GPU byte-equality on N=1000 random precompile calls with k ∈ {1, 2, 4, 8, 16}; PASS.

Test oracle

• go-ethereum core/vm/contracts.go precompile reference (test-only, FetchContent)
• Ethereum execution-spec-tests EIP-196/197 vectors

Security

• Subgroup check enforced for both G1 and G2 inputs (defense vs invalid-curve attack)
• Gas-metered: long pairings are charged proportional to k to prevent DOS
• Constant-time inherited from LP-146 BN254

References

• EIP-196 (ECADD/ECMUL precompile)
• EIP-197 (ECPAIRING precompile)
• EIP-1108 (Istanbul gas-cost reduction)
• LP-146 (BN254 — underlying curve)
• LP-137 (umbrella)