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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 = '2';
const EIP712_VALUE_LENGTH = 32;
const EIP712_DOMAIN_SCHEMA: EIP712Schema = {
name: 'DomainSeparator',
parameters: [
{ name: 'name', type: 'string' },
{ name: 'version', type: 'string' },
{ name: 'contract', type: 'address' },
],
};
export const EIP712Utils = {
/**
* Compiles the EIP712Schema and returns the hash of the schema.
* @param schema The EIP712 schema.
* @return The hash of the compiled schema
*/
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;
},
/**
* Merges the EIP712 hash of a struct with the DomainSeparator for 0x v2.
* @param hashStruct the EIP712 hash of a struct
* @param contractAddress the exchange contract address
* @return The hash of an EIP712 message with domain separator prefixed
*/
createEIP712Message(hashStruct: Buffer, contractAddress: string): Buffer {
const domainSeparatorHashBuffer = EIP712Utils._getDomainSeparatorHashBuffer(contractAddress);
const messageBuff = crypto.solSHA3([EIP191_PREFIX, domainSeparatorHashBuffer, hashStruct]);
return messageBuff;
},
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, EIP712_VALUE_LENGTH);
return bufferPadded;
},
_getDomainSeparatorSchemaBuffer(): Buffer {
return EIP712Utils.compileSchema(EIP712_DOMAIN_SCHEMA);
},
_getDomainSeparatorHashBuffer(exchangeAddress: string): Buffer {
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),
]);
return domainSeparatorHashBuff;
},
};
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