218 lines
8.6 KiB
JavaScript
218 lines
8.6 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.bn254_weierstrass = exports.bn254 = exports._postPrecompute = exports.bn254_Fr = void 0;
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/**
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* bn254, previously known as alt_bn_128, when it had 128-bit security.
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Barbulescu-Duquesne 2017 shown it's weaker: just about 100 bits,
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so the naming has been adjusted to its prime bit count:
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https://hal.science/hal-01534101/file/main.pdf.
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Compatible with EIP-196 and EIP-197.
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There are huge compatibility issues in the ecosystem:
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1. Different libraries call it in different ways: "bn254", "bn256", "alt_bn128", "bn128".
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2. libff has bn128, but it's a different curve with different G2:
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https://github.com/scipr-lab/libff/blob/a44f482e18b8ac04d034c193bd9d7df7817ad73f/libff/algebra/curves/bn128/bn128_init.cpp#L166-L169
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3. halo2curves bn256 is also incompatible and returns different outputs
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We don't implement Point methods toHex / toBytes.
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To work around this limitation, has to initialize points on their own from BigInts.
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Reason it's not implemented is because [there is no standard](https://github.com/privacy-scaling-explorations/halo2curves/issues/109).
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Points of divergence:
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- Endianness: LE vs BE (byte-swapped)
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- Flags as first hex bits (similar to BLS) vs no-flags
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- Imaginary part last in G2 vs first (c0, c1 vs c1, c0)
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The goal of our implementation is to support "Ethereum" variant of the curve,
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because it at least has specs:
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- EIP196 (https://eips.ethereum.org/EIPS/eip-196) describes bn254 ECADD and ECMUL opcodes for EVM
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- EIP197 (https://eips.ethereum.org/EIPS/eip-197) describes bn254 pairings
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- It's hard: EIPs don't have proper tests. EIP-197 returns boolean output instead of Fp12
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- The existing implementations are bad. Some are deprecated:
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- https://github.com/paritytech/bn (old version)
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- https://github.com/ewasm/ethereum-bn128.rs (uses paritytech/bn)
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- https://github.com/zcash-hackworks/bn
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- https://github.com/arkworks-rs/curves/blob/master/bn254/src/lib.rs
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- Python implementations use different towers and produce different Fp12 outputs:
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- https://github.com/ethereum/py_pairing
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- https://github.com/ethereum/execution-specs/blob/master/src/ethereum/crypto/alt_bn128.py
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- Points are encoded differently in different implementations
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### Params
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Seed (X): 4965661367192848881
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Fr: (36x⁴+36x³+18x²+6x+1)
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Fp: (36x⁴+36x³+24x²+6x+1)
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(E / Fp ): Y² = X³+3
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(Et / Fp²): Y² = X³+3/(u+9) (D-type twist)
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Ate loop size: 6x+2
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### Towers
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- Fp²[u] = Fp/u²+1
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- Fp⁶[v] = Fp²/v³-9-u
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- Fp¹²[w] = Fp⁶/w²-v
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* @module
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*/
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/*! noble-curves - MIT License (c) 2022 Paul Miller (paulmillr.com) */
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const sha2_js_1 = require("@noble/hashes/sha2.js");
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const bls_ts_1 = require("./abstract/bls.js");
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const modular_ts_1 = require("./abstract/modular.js");
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const tower_ts_1 = require("./abstract/tower.js");
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const weierstrass_ts_1 = require("./abstract/weierstrass.js");
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const utils_ts_1 = require("./utils.js");
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// prettier-ignore
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const _0n = BigInt(0), _1n = BigInt(1), _2n = BigInt(2), _3n = BigInt(3);
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const _6n = BigInt(6);
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const BN_X = BigInt('4965661367192848881');
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const BN_X_LEN = (0, utils_ts_1.bitLen)(BN_X);
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const SIX_X_SQUARED = _6n * BN_X ** _2n;
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const bn254_G1_CURVE = {
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p: BigInt('0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47'),
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n: BigInt('0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001'),
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h: _1n,
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a: _0n,
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b: _3n,
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Gx: _1n,
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Gy: BigInt(2),
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};
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// r == n
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// Finite field over r. It's for convenience and is not used in the code below.
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exports.bn254_Fr = (0, modular_ts_1.Field)(bn254_G1_CURVE.n);
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// Fp2.div(Fp2.mul(Fp2.ONE, _3n), Fp2.NONRESIDUE)
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const Fp2B = {
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c0: BigInt('19485874751759354771024239261021720505790618469301721065564631296452457478373'),
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c1: BigInt('266929791119991161246907387137283842545076965332900288569378510910307636690'),
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};
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const { Fp, Fp2, Fp6, Fp12 } = (0, tower_ts_1.tower12)({
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ORDER: bn254_G1_CURVE.p,
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X_LEN: BN_X_LEN,
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FP2_NONRESIDUE: [BigInt(9), _1n],
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Fp2mulByB: (num) => Fp2.mul(num, Fp2B),
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Fp12finalExponentiate: (num) => {
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const powMinusX = (num) => Fp12.conjugate(Fp12._cyclotomicExp(num, BN_X));
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const r0 = Fp12.mul(Fp12.conjugate(num), Fp12.inv(num));
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const r = Fp12.mul(Fp12.frobeniusMap(r0, 2), r0);
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const y1 = Fp12._cyclotomicSquare(powMinusX(r));
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const y2 = Fp12.mul(Fp12._cyclotomicSquare(y1), y1);
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const y4 = powMinusX(y2);
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const y6 = powMinusX(Fp12._cyclotomicSquare(y4));
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const y8 = Fp12.mul(Fp12.mul(Fp12.conjugate(y6), y4), Fp12.conjugate(y2));
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const y9 = Fp12.mul(y8, y1);
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return Fp12.mul(Fp12.frobeniusMap(Fp12.mul(Fp12.conjugate(r), y9), 3), Fp12.mul(Fp12.frobeniusMap(y8, 2), Fp12.mul(Fp12.frobeniusMap(y9, 1), Fp12.mul(Fp12.mul(y8, y4), r))));
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},
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});
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// END OF CURVE FIELDS
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const { G2psi, psi } = (0, tower_ts_1.psiFrobenius)(Fp, Fp2, Fp2.NONRESIDUE);
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/*
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No hashToCurve for now (and signatures):
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- RFC 9380 doesn't mention bn254 and doesn't provide test vectors
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- Overall seems like nobody is using BLS signatures on top of bn254
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- Seems like it can utilize SVDW, which is not implemented yet
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*/
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const htfDefaults = Object.freeze({
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// DST: a domain separation tag defined in section 2.2.5
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DST: 'BN254G2_XMD:SHA-256_SVDW_RO_',
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encodeDST: 'BN254G2_XMD:SHA-256_SVDW_RO_',
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p: Fp.ORDER,
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m: 2,
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k: 128,
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expand: 'xmd',
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hash: sha2_js_1.sha256,
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});
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const _postPrecompute = (Rx, Ry, Rz, Qx, Qy, pointAdd) => {
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const q = psi(Qx, Qy);
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({ Rx, Ry, Rz } = pointAdd(Rx, Ry, Rz, q[0], q[1]));
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const q2 = psi(q[0], q[1]);
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pointAdd(Rx, Ry, Rz, q2[0], Fp2.neg(q2[1]));
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};
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exports._postPrecompute = _postPrecompute;
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// cofactor: (36 * X^4) + (36 * X^3) + (30 * X^2) + 6*X + 1
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const bn254_G2_CURVE = {
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p: Fp2.ORDER,
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n: bn254_G1_CURVE.n,
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h: BigInt('0x30644e72e131a029b85045b68181585e06ceecda572a2489345f2299c0f9fa8d'),
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a: Fp2.ZERO,
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b: Fp2B,
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Gx: Fp2.fromBigTuple([
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BigInt('10857046999023057135944570762232829481370756359578518086990519993285655852781'),
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BigInt('11559732032986387107991004021392285783925812861821192530917403151452391805634'),
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]),
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Gy: Fp2.fromBigTuple([
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BigInt('8495653923123431417604973247489272438418190587263600148770280649306958101930'),
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BigInt('4082367875863433681332203403145435568316851327593401208105741076214120093531'),
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]),
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};
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/**
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* bn254 (a.k.a. alt_bn128) pairing-friendly curve.
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* Contains G1 / G2 operations and pairings.
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*/
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exports.bn254 = (0, bls_ts_1.bls)({
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// Fields
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fields: { Fp, Fp2, Fp6, Fp12, Fr: exports.bn254_Fr },
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G1: {
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...bn254_G1_CURVE,
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Fp,
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htfDefaults: { ...htfDefaults, m: 1, DST: 'BN254G2_XMD:SHA-256_SVDW_RO_' },
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wrapPrivateKey: true,
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allowInfinityPoint: true,
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mapToCurve: utils_ts_1.notImplemented,
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fromBytes: utils_ts_1.notImplemented,
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toBytes: utils_ts_1.notImplemented,
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ShortSignature: {
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fromBytes: utils_ts_1.notImplemented,
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fromHex: utils_ts_1.notImplemented,
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toBytes: utils_ts_1.notImplemented,
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toRawBytes: utils_ts_1.notImplemented,
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toHex: utils_ts_1.notImplemented,
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},
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},
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G2: {
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...bn254_G2_CURVE,
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Fp: Fp2,
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hEff: BigInt('21888242871839275222246405745257275088844257914179612981679871602714643921549'),
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htfDefaults: { ...htfDefaults },
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wrapPrivateKey: true,
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allowInfinityPoint: true,
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isTorsionFree: (c, P) => P.multiplyUnsafe(SIX_X_SQUARED).equals(G2psi(c, P)), // [p]P = [6X^2]P
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mapToCurve: utils_ts_1.notImplemented,
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fromBytes: utils_ts_1.notImplemented,
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toBytes: utils_ts_1.notImplemented,
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Signature: {
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fromBytes: utils_ts_1.notImplemented,
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fromHex: utils_ts_1.notImplemented,
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toBytes: utils_ts_1.notImplemented,
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toRawBytes: utils_ts_1.notImplemented,
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toHex: utils_ts_1.notImplemented,
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},
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},
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params: {
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ateLoopSize: BN_X * _6n + _2n,
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r: exports.bn254_Fr.ORDER,
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xNegative: false,
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twistType: 'divisive',
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},
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htfDefaults,
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hash: sha2_js_1.sha256,
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postPrecompute: exports._postPrecompute,
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});
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/**
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* bn254 weierstrass curve with ECDSA.
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* This is very rare and probably not used anywhere.
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* Instead, you should use G1 / G2, defined above.
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* @deprecated
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*/
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exports.bn254_weierstrass = (0, weierstrass_ts_1.weierstrass)({
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a: BigInt(0),
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b: BigInt(3),
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Fp,
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n: BigInt('21888242871839275222246405745257275088548364400416034343698204186575808495617'),
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Gx: BigInt(1),
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Gy: BigInt(2),
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h: BigInt(1),
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hash: sha2_js_1.sha256,
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});
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//# sourceMappingURL=bn254.js.map
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