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stark: switch to new weierstrass methods

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This commit is contained in:
Paul Miller 2023-01-23 22:07:21 +00:00
parent a2c87f9c2f
commit ceb3f67faa
No known key found for this signature in database
GPG Key ID: 697079DA6878B89B
2 changed files with 292 additions and 284 deletions
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42
src/stark.ts
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@ -16,6 +16,15 @@ const CURVE_N = BigInt(
'3618502788666131213697322783095070105526743751716087489154079457884512865583'
);
const nBitLength = 252;
// Copy-pasted from weierstrass.ts
function bits2int(bytes: Uint8Array): bigint {
const delta = bytes.length * 8 - nBitLength;
const num = cutils.bytesToNumberBE(bytes);
return delta > 0 ? num >> BigInt(delta) : num;
}
function bits2int_modN(bytes: Uint8Array): bigint {
return mod(bits2int(bytes), CURVE_N);
}
export const starkCurve = weierstrass({
// Params: a, b
a: BigInt(1),
@ -33,24 +42,20 @@ export const starkCurve = weierstrass({
// Default options
lowS: false,
...getHash(sha256),
truncateHash: (hash: Uint8Array, truncateOnly = false): Uint8Array => {
// Fix truncation
if (!truncateOnly) {
let hashS = bytesToNumber0x(hash).toString(16);
// Custom truncation routines for stark curve
bits2int: (bytes: Uint8Array): bigint => {
while (bytes[0] === 0) bytes = bytes.subarray(1);
return bits2int(bytes);
},
bits2int_modN: (bytes: Uint8Array): bigint => {
let hashS = cutils.bytesToNumberBE(bytes).toString(16);
if (hashS.length === 63) {
hashS += '0';
hash = hexToBytes0x(hashS);
}
bytes = hexToBytes0x(hashS);
}
// Truncate zero bytes on left (compat with elliptic)
while (hash[0] === 0) hash = hash.subarray(1);
// bits2int + part of bits2octets (mod if !truncateOnly)
const byteLength = hash.length;
const delta = byteLength * 8 - nBitLength; // size of curve.n (252 bits)
let h = hash.length ? bytesToNumber0x(hash) : 0n;
if (delta > 0) h = h >> BigInt(delta); // truncate to nBitLength leftmost bits
if (!truncateOnly) h = mod(h, CURVE_N);
return cutils.numberToVarBytesBE(h);
while (bytes[0] === 0) bytes = bytes.subarray(1);
return bits2int_modN(bytes);
},
});
@ -134,7 +139,7 @@ type Hex = Uint8Array | string;
function hashKeyWithIndex(key: Uint8Array, index: number) {
let indexHex = cutils.numberToHexUnpadded(index);
if (indexHex.length & 1) indexHex = '0' + indexHex;
return bytesToNumber0x(sha256(cutils.concatBytes(key, hexToBytes0x(indexHex))));
return sha256Num(cutils.concatBytes(key, hexToBytes0x(indexHex)));
}
export function grindKey(seed: Hex) {
@ -167,8 +172,8 @@ export function getAccountPath(
ethereumAddress: string,
index: number
) {
const layerNum = int31(bytesToNumber0x(sha256(layer)));
const applicationNum = int31(bytesToNumber0x(sha256(application)));
const layerNum = int31(sha256Num(layer));
const applicationNum = int31(sha256Num(application));
const eth = hexToNumber0x(ethereumAddress);
return `m/2645'/${layerNum}'/${applicationNum}'/${int31(eth)}'/${int31(eth >> 31n)}'/${index}`;
}
@ -264,7 +269,8 @@ export const computeHashOnElements = (data: PedersenArg[], fn = pedersen) =>
[0, ...data, data.length].reduce((x, y) => fn(x, y));
const MASK_250 = cutils.bitMask(250);
export const keccak = (data: Uint8Array) => bytesToNumber0x(keccak_256(data)) & MASK_250;
export const keccak = (data: Uint8Array): bigint => bytesToNumber0x(keccak_256(data)) & MASK_250;
const sha256Num = (data: Uint8Array | string): bigint => cutils.bytesToNumberBE(sha256(data));
// Poseidon hash
export const Fp253 = Fp(

6
test/stark/stark.test.js
View File

@ -1,5 +1,5 @@
import { deepStrictEqual, throws } from 'assert';
import { should } from 'micro-should';
import { describe, should } from 'micro-should';
import { hex, utf8 } from '@scure/base';
import * as bip32 from '@scure/bip32';
import * as bip39 from '@scure/bip39';
@ -7,7 +7,8 @@ import * as starknet from '../../lib/esm/stark.js';
import { default as sigVec } from './fixtures/rfc6979_signature_test_vector.json' assert { type: 'json' };
import { default as precomputedKeys } from './fixtures/keys_precomputed.json' assert { type: 'json' };
should('Starknet keccak', () => {
describe('starknet', () => {
should('custom keccak', () => {
const value = starknet.keccak(utf8.decode('hello'));
deepStrictEqual(value, 0x8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8n);
deepStrictEqual(value < 2n ** 250n, true);
@ -278,6 +279,7 @@ should('Starknet.js cross-tests', () => {
);
deepStrictEqual(starknet.verify(sig2.toDERHex(), hashMsg2, pubKey), true);
});
});
// ESM is broken.
import url from 'url';