import * as BigNumber from 'bignumber.js'; import * as ethUtil from 'ethereumjs-util'; import * as _ from 'lodash'; import {assert} from './utils/assert'; import {ECSignatureSchema} from './schemas/ec_signature_schema'; /** * Elliptic Curve signature */ export interface ECSignature { v: number; r: string; s: string; } const MAX_DIGITS_IN_UNSIGNED_256_INT = 78; export class ZeroEx { /** * Verifies that the elliptic curve signature `signature` was generated * by signing `data` with the private key corresponding to the `signer` address. */ public static isValidSignature(dataHex: string, signature: ECSignature, signerETHAddressHex: string): boolean { assert.isHexString('dataHex', dataHex); assert.doesConformToSchema('signature', signature, ECSignatureSchema); assert.isETHAddressHex('signerAddress', signerETHAddressHex); const dataBuff = ethUtil.toBuffer(dataHex); const msgHashBuff = ethUtil.hashPersonalMessage(dataBuff); try { const pubKey = ethUtil.ecrecover(msgHashBuff, signature.v, ethUtil.toBuffer(signature.r), ethUtil.toBuffer(signature.s)); const retrievedAddress = ethUtil.bufferToHex(ethUtil.pubToAddress(pubKey)); return retrievedAddress === signerETHAddressHex; } catch (err) { return false; } } /** * Generates pseudo-random 256 bit salt. * The salt is used to ensure that the 0x order generated has a unique orderHash that does * not collide with any other outstanding orders. */ public static generatePseudoRandomSalt(): BigNumber.BigNumber { // BigNumber.random returns a pseudo-random number between 0 & 1 with a passed in number of decimal places. // Source: https://mikemcl.github.io/bignumber.js/#random const randomNumber = BigNumber.random(MAX_DIGITS_IN_UNSIGNED_256_INT); const factor = new BigNumber(10).pow(MAX_DIGITS_IN_UNSIGNED_256_INT - 1); const salt = randomNumber.times(factor).round(); return salt; } /** Checks if order hash is valid */ public static isValidOrderHash(orderHash: string): boolean { assert.isString('orderHash', orderHash); const isValid = /^0x[0-9A-F]{66}$/i.test(orderHash); return isValid; /* * A unit amount is defined as the amount of a token above the specified decimal places (integer part). * E.g: If a currency has 18 decimal places, 1e18 or one quintillion of the currency is equivalent * to 1 unit. */ public static toUnitAmount(amount: BigNumber.BigNumber, decimals: number): BigNumber.BigNumber { assert.isBigNumber('amount', amount); assert.isNumber('decimals', decimals); const aUnit = new BigNumber(10).pow(decimals); const unit = amount.div(aUnit); return unit; } /* * A baseUnit is defined as the smallest denomination of a token. An amount expressed in baseUnits * is the amount expressed in the smallest denomination. * E.g: 1 unit of a token with 18 decimal places is expressed in baseUnits as 1000000000000000000 */ public static toBaseUnitAmount(amount: BigNumber.BigNumber, decimals: number): BigNumber.BigNumber { assert.isBigNumber('amount', amount); assert.isNumber('decimals', decimals); const unit = new BigNumber(10).pow(decimals); const baseUnitAmount = amount.times(unit); return baseUnitAmount; } }