forked from tornado-packages/noble-curves
59 lines
2.3 KiB
TypeScript
59 lines
2.3 KiB
TypeScript
/*! noble-curves - MIT License (c) 2022 Paul Miller (paulmillr.com) */
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import { sha512 } from '@noble/hashes/sha512';
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import { concatBytes, randomBytes, utf8ToBytes } from '@noble/hashes/utils';
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import { twistedEdwards } from './abstract/edwards.js';
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import { blake2s } from '@noble/hashes/blake2s';
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import { Fp } from './abstract/modular.js';
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/**
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* jubjub Twisted Edwards curve.
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* https://neuromancer.sk/std/other/JubJub
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* jubjub does not use EdDSA, so `hash`/sha512 params are passed because interface expects them.
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*/
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export const jubjub = twistedEdwards({
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// Params: a, d
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a: BigInt('0x73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000000'),
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d: BigInt('0x2a9318e74bfa2b48f5fd9207e6bd7fd4292d7f6d37579d2601065fd6d6343eb1'),
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// Finite field 𝔽p over which we'll do calculations
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// Same value as bls12-381 Fr (not Fp)
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Fp: Fp(BigInt('0x73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001')),
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// Subgroup order: how many points curve has
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n: BigInt('0xe7db4ea6533afa906673b0101343b00a6682093ccc81082d0970e5ed6f72cb7'),
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// Cofactor
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h: BigInt(8),
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// Base point (x, y) aka generator point
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Gx: BigInt('0x11dafe5d23e1218086a365b99fbf3d3be72f6afd7d1f72623e6b071492d1122b'),
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Gy: BigInt('0x1d523cf1ddab1a1793132e78c866c0c33e26ba5cc220fed7cc3f870e59d292aa'),
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hash: sha512,
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randomBytes,
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} as const);
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const GH_FIRST_BLOCK = utf8ToBytes(
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'096b36a5804bfacef1691e173c366a47ff5ba84a44f26ddd7e8d9f79d5b42df0'
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);
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// Returns point at JubJub curve which is prime order and not zero
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export function groupHash(tag: Uint8Array, personalization: Uint8Array) {
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const h = blake2s.create({ personalization, dkLen: 32 });
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h.update(GH_FIRST_BLOCK);
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h.update(tag);
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// NOTE: returns ExtendedPoint, in case it will be multiplied later
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let p = jubjub.ExtendedPoint.fromHex(h.digest());
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// NOTE: cannot replace with isSmallOrder, returns Point*8
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p = p.multiply(jubjub.CURVE.h);
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if (p.equals(jubjub.ExtendedPoint.ZERO)) throw new Error('Point has small order');
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return p;
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}
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export function findGroupHash(m: Uint8Array, personalization: Uint8Array) {
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const tag = concatBytes(m, new Uint8Array([0]));
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for (let i = 0; i < 256; i++) {
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tag[tag.length - 1] = i;
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try {
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return groupHash(tag, personalization);
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} catch (e) {}
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}
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throw new Error('findGroupHash tag overflow');
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}
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