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Sign In With Ethereum

AppKit provides a simple solution for integrating with "Sign In With Ethereum" (SIWE), a new form of authentication that enables users to control their digital identity with their Ethereum account. SIWE is a standard also known as EIP-4361.

One-Click Auth

One-Click Auth represents a key advancement within WalletConnect v2, streamlining the user authentication process in Web3Modal by enabling them to seamlessly connect with a wallet and sign a SIWE message with just one click.

Connecting a wallet, proving control of an address with an off-chain signature, authorizing specific actions. These are the kinds of authorizations that can be encoded as "ReCaps". ReCaps are permissions for a specific website or dapp that can be compactly encoded as a long string in the message you sign and translated by any wallet into a straight-forward one-sentence summary. WalletConnect uses permissions expressed as ReCaps to enable a One-Click Authentication.


In order for SIWE to work, you need to have a backend to communicate with. This backend will be used to generate a nonce, verify messages and handle sessions. More info here


This feature is currently in beta. To get it, change your dependency to use web3modal_flutter: ^3.3.0-beta06

Configure your SIWEConfig object

final _siweConfig = SIWEConfig(
getNonce: () async {
// The getNonce method functions as a safeguard
// against spoofing, akin to a CSRF token.

return await yourApi.getNonce();
getMessageParams: () async {
// Parameters to create the SIWE message internally.
// More info in

return SIWEMessageArgs(
domain: '',
uri: '',
statement: 'Please sign with your account',
methods: ['personal_sign', 'eth_sendTransaction'],
createMessage: (SIWECreateMessageArgs args) {
// Method for generating an EIP-4361-compatible message.
// You can use our provided formatMessage() method or implement your own

return AuthSignature.formatMessage(args);
verifyMessage: (SIWEVerifyMessageArgs args) async {
// This function ensures the message is valid,
// has not been tampered with, and has been appropriately
// signed by the wallet address.

try {
final isValidMessage = await yourApi.verifyMessage(args.toJson());
return isValidMessage;
} catch (error) {
// error validating message
return false;
getSession: () async {
// Called after verifyMessage() succeeds
// The backend session should store the associated address and chainId
// and return it via the `getSession` method.

try {
final session = await yourApi.getSession();
return SIWESession(address: session.address, chains: [session.chainId]);
} catch (error) {
// error getting session
onSignIn: (SIWESession session) {
// Called after getSession() succeeds
signOut: () async {
// Called when wallet disconnects if `signOutOnDisconnect == true` and/or when
// `signOutOnAccountChange == true` and/or
// `signOutOnNetworkChange == true`
try {
final success = await yourApi.signOut();
return success;
} catch (error) {
// error signing out
return false;
onSignOut: () {
// Called after signOut() succeeds
// enabled: true, // OPTIONAL. Enables One-Click Auth + SIWE logic, if `false`, regular session proposal will be used. (default `true`)
// signOutOnDisconnect: true, // OPTIONAL (default `true`)
// signOutOnAccountChange: true, // OPTIONAL (default `true`)
// signOutOnNetworkChange: true, // OPTIONAL (default `true`)

Initialize Web3Modal with your siweConfig

Add the siwe configuration in W3MService initialization


If siweConfig: is used then W3MService object will require a BuildContext context parameter to be passed.

final _w3mService = W3MService(
context: context,
projectId: '{YOUR_PROJECT_ID}',
metadata: const PairingMetadata(
siweConfig: _siweConfig, // not setting `siweConfig` hast the same effect as setting `false` on `siweConfig.enable`

SIWEConfig reference

class SIWEConfig {
final Future<String> Function() getNonce;
final Future<SIWEMessageArgs> Function() getMessageParams;
final String Function(SIWECreateMessageArgs args) createMessage;
final Future<bool> Function(SIWEVerifyMessageArgs args) verifyMessage;
final Future<SIWESession?> Function() getSession;
final Future<bool> Function() signOut;
// Callback when user signs in
final Function(SIWESession session)? onSignIn;
// Callback when user signs out
final VoidCallback? onSignOut;
// Defaults to true
final bool enabled;
// In milliseconds, defaults to 5 minutes
final int nonceRefetchIntervalMs;
// In milliseconds, defaults to 5 minutes
final int sessionRefetchIntervalMs;
// Defaults to true
final bool signOutOnDisconnect;
// Defaults to true
final bool signOutOnAccountChange;
// Defaults to true
final bool signOutOnNetworkChange;

required this.getNonce,
required this.getMessageParams,
required this.createMessage,
required this.verifyMessage,
required this.getSession,
required this.signOut,
this.enabled = true,
this.signOutOnDisconnect = true,
this.signOutOnAccountChange = true,
this.signOutOnNetworkChange = true,
this.nonceRefetchIntervalMs = 300000,
this.sessionRefetchIntervalMs = 300000,

Exported functions


Simple method to generate a timestamp-based nonce



Creates EIP-4361 message based on input arguments.



Verify a SIWE signature. Internally it calls your backend verification method.

await AuthSignature.verifySignature(


Get the chain ID from the SIWE message.



Get the address from the SIWE message.