vyperlang/vyper

VIP: Add support for Alt_Bn128 precompile curve operations

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#1,650 opened on Oct 24, 2019

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VIP: Approvedenhancementhelp wanted

Description

Simple Summary

Add support for precompiled opcode for alt_bn128 pairing calculation

Motivation

We already have support for ecadd and ecmul which perform the corresponding alt_bn128 curve operations (and which should perhaps be renamed to bn128_ecadd and bn128_ecmul), but we do not have support for bn128 pairing operations, which allows the verification of Zero-Knowledge proofs using the alt-bn128 curve, such as in zk-SNARK implementations. This would allow ZKP verifier contracts to be created in Vyper (such as the ones ZoKrates can create).

Specification

alt-bn128 elliptic curve pairing operations were already added as of Byzantium via EIP-197 (with gas costs to be updated in Istanbul via EIP-1108). A reference implementation is provided here: https://github.com/ethereum/py-evm/blob/master/eth/precompiles/ecpairing.py

Backwards Compatibility

No backwards incompatibilities

Dependencies

No dependencies

Copyright

Copyright and related rights waived via CC0

Contributor guide

Tech stack
python
Domain
blockchainsecurity
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
elliptic curve cryptographyEVM precompilesVyper internalsEIP 197
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Implement the alt bn128 pairing precompile (ecpairing) as specified in EIP 197. Reference the existing implementation at https://github.com/ethereum/py evm/blob/master/eth/precompiles/ecpairing.py. Currently, Vyper supports ecadd and ecmul for alt bn128; these may need renaming to bn128 ecadd and bn128 ecmul for consistency. The implementation should follow the same pattern as existing precompiles in Vyper's compiler, likely in the code generation or built in functions area. No linked PRs or assignees, so this issue is open for contribution.