Client and backend. This class is shared: the same code is compiled into your app and into your server, so everything on this page works in both.

public final class TypedData

Object
TypedData

EIP-712 typed structured data: the eth_signTypedData_v4 document permits, orders and meta-transactions are signed as.

String jsonFromTheDapp = "{...}";           // the eth_signTypedData_v4 argument
byte[] privateKey = SecureRandom.bytes(32);
TypedData doc = TypedData.fromJson(jsonFromTheDapp);
byte[] signature = doc.sign(privateKey);      // r || s || v

The document is the JSON a dapp sends: types, primaryType, domain and message. When types omits EIP712Domain, it is derived from the domain fields present, as wallets do.

Constructors

public TypedData(Map<String, List<String[]>> types, String primaryType, Map<String, Object> domain, Map<String, Object> message) A document from its parts.

Methods

`public static` `TypedData fromJson(String json)`	Reads the `eth_signTypedData_v4` JSON document.
`public byte[] hash()`	The 32-byte digest a wallet signs: `keccak256(0x1901 \|\| domainSeparator \|\| hashStruct(message))`.
`public byte[] domainSeparator()`	`hashStruct(EIP712Domain, domain)`.
`public byte[] messageHash()`	The `hashStruct` of the message.
`public byte[] sign(byte[] privateKey)`	Signs the document, answering `r \|\| s \|\| v` with `v` 27 or 28.
`public` `EvmAddress recover(byte[] signature65)`	The address that signed the document.
`public` `String encodeType(String type)`	The `encodeType` string of a struct, such as `Mail(Person from,Person to,string contents)Person(string name,address wallet)`.
`public byte[] hashStruct(String type, Map<String, Object> value)`	`keccak256(typeHash \|\| encodeData(value))` of a struct.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone, finalize

Constructor details

TypedData

public TypedData(Map<String, List<String[]>> types, String primaryType, Map<String, Object> domain, Map<String, Object> message)

A document from its parts.

Parameters

types Map<String, List<String[]>>: struct name to its members, each {name, type}, in declaration order
primaryType String: the struct message is an instance of
domain Map<String, Object>: the EIP712Domain values
message Map<String, Object>: the values of the primary struct

Method details

fromJson

public static TypedData fromJson(String json)

Reads the eth_signTypedData_v4 JSON document.

Throws

IllegalArgumentException: for malformed JSON or a document missing a part

hash

public byte[] hash()

The 32-byte digest a wallet signs: keccak256(0x1901 || domainSeparator || hashStruct(message)).

domainSeparator

public byte[] domainSeparator()

hashStruct(EIP712Domain, domain).

messageHash

public byte[] messageHash()

The hashStruct of the message.

sign

public byte[] sign(byte[] privateKey)

Signs the document, answering r || s || v with v 27 or 28.

recover

public EvmAddress recover(byte[] signature65)

The address that signed the document.

encodeType

public String encodeType(String type)

The encodeType string of a struct, such as Mail(Person from,Person to,string contents)Person(string name,address wallet).

hashStruct

public byte[] hashStruct(String type, Map<String, Object> value)

keccak256(typeHash || encodeData(value)) of a struct.