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import { BigNumber } from '@0xproject/utils';
import ethUtil = require('ethereumjs-util');
import * as _ from 'lodash';
import { crypto } from './crypto';
import { EIP712Schema } from './types';
const EIP191_PREFIX = '\x19\x01';
const EIP712_DOMAIN_NAME = '0x Protocol';
const EIP712_DOMAIN_VERSION = '1';
const EIP712_DOMAIN_SCHEMA: EIP712Schema = {
name: 'DomainSeparator',
parameters: [
{ name: 'name', type: 'string' },
{ name: 'version', type: 'string' },
{ name: 'contract', type: 'address' },
],
};
export const EIP712Utils = {
compileSchema(schema: EIP712Schema): Buffer {
const namedTypes = _.map(schema.parameters, parameter => `${parameter.type} ${parameter.name}`);
const namedTypesJoined = namedTypes.join(',');
const eip712Schema = `${schema.name}(${namedTypesJoined})`;
const eip712SchemaHashBuffer = crypto.solSHA3([eip712Schema]);
return eip712SchemaHashBuffer;
},
createEIP712Message(hashStruct: string, contractAddress: string): Buffer {
const domainSeparatorHashHex = EIP712Utils.getDomainSeparatorHashHex(contractAddress);
const messageBuff = crypto.solSHA3([
EIP191_PREFIX,
new BigNumber(domainSeparatorHashHex),
new BigNumber(hashStruct),
]);
return messageBuff;
},
getDomainSeparatorSchemaBuffer(): Buffer {
return EIP712Utils.compileSchema(EIP712_DOMAIN_SCHEMA);
},
getDomainSeparatorHashHex(exchangeAddress: string): string {
const domainSeparatorSchemaBuffer = EIP712Utils.getDomainSeparatorSchemaBuffer();
const nameHash = crypto.solSHA3([EIP712_DOMAIN_NAME]);
const versionHash = crypto.solSHA3([EIP712_DOMAIN_VERSION]);
const domainSeparatorHashBuff = crypto.solSHA3([
domainSeparatorSchemaBuffer,
nameHash,
versionHash,
EIP712Utils.pad32Address(exchangeAddress),
]);
const domainSeparatorHashHex = `0x${domainSeparatorHashBuff.toString('hex')}`;
return domainSeparatorHashHex;
},
pad32Address(address: string): Buffer {
const addressBuffer = ethUtil.toBuffer(address);
const addressPadded = EIP712Utils.pad32Buffer(addressBuffer);
return addressPadded;
},
pad32Buffer(buffer: Buffer): Buffer {
const bufferPadded = ethUtil.setLengthLeft(buffer, 32);
return bufferPadded;
},
};
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