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import ethUtil = require('ethereumjs-util');
import * as _ from 'lodash';
import { crypto } from './crypto';
import { EIP712Schema, EIP712Types } 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: 'EIP712Domain',
parameters: [
{ name: 'name', type: EIP712Types.String },
{ name: 'version', type: EIP712Types.String },
{ name: 'verifyingContract', type: EIP712Types.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 eip712Schema = eip712Utils._encodeType(schema);
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;
},
/**
* Pad an address to 32 bytes
* @param address Address to pad
* @return padded address
*/
pad32Address(address: string): Buffer {
const addressBuffer = ethUtil.toBuffer(address);
const addressPadded = eip712Utils.pad32Buffer(addressBuffer);
return addressPadded;
},
/**
* Pad an buffer to 32 bytes
* @param buffer Address to pad
* @return padded buffer
*/
pad32Buffer(buffer: Buffer): Buffer {
const bufferPadded = ethUtil.setLengthLeft(buffer, EIP712_VALUE_LENGTH);
return bufferPadded;
},
/**
* Hash together a EIP712 schema with the corresponding data
* @param schema EIP712-compliant schema
* @param data Data the complies to the schema
* @return A buffer containing the SHA256 hash of the schema and encoded data
*/
structHash(schema: EIP712Schema, data: { [key: string]: any }): Buffer {
const encodedData = eip712Utils._encodeData(schema, data);
const schemaHash = eip712Utils.compileSchema(schema);
const hashBuffer = crypto.solSHA3([schemaHash, ...encodedData]);
return hashBuffer;
},
_getDomainSeparatorSchemaBuffer(): Buffer {
return eip712Utils.compileSchema(EIP712_DOMAIN_SCHEMA);
},
_getDomainSeparatorHashBuffer(exchangeAddress: string): Buffer {
const domainSeparatorSchemaBuffer = eip712Utils._getDomainSeparatorSchemaBuffer();
const encodedData = eip712Utils._encodeData(EIP712_DOMAIN_SCHEMA, {
name: EIP712_DOMAIN_NAME,
version: EIP712_DOMAIN_VERSION,
verifyingContract: exchangeAddress,
});
const domainSeparatorHashBuff2 = crypto.solSHA3([domainSeparatorSchemaBuffer, ...encodedData]);
return domainSeparatorHashBuff2;
},
_encodeType(schema: EIP712Schema): string {
const namedTypes = _.map(schema.parameters, ({ name, type }) => `${type} ${name}`);
const namedTypesJoined = namedTypes.join(',');
const encodedType = `${schema.name}(${namedTypesJoined})`;
return encodedType;
},
_encodeData(schema: EIP712Schema, data: { [key: string]: any }): any {
const encodedValues = [];
for (const parameter of schema.parameters) {
const value = data[parameter.name];
if (parameter.type === EIP712Types.String || parameter.type === EIP712Types.Bytes) {
encodedValues.push(crypto.solSHA3([ethUtil.toBuffer(value)]));
} else if (parameter.type === EIP712Types.Uint256) {
encodedValues.push(value);
} else if (parameter.type === EIP712Types.Address) {
encodedValues.push(eip712Utils.pad32Address(value));
} else {
throw new Error(`Unable to encode ${parameter.type}`);
}
}
return encodedValues;
},
};
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