> ## Documentation Index
> Fetch the complete documentation index at: https://stytch.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Authenticate Start

> Authenticate Start using the Stytch Next.js SDK

Wraps the [Crypto Wallet Authenticate Start](/docs/api-reference/consumer/api/crypto-wallets/authenticate-start) endpoint. Call this method to prompt the user to sign a challenge using their crypto wallet. For Ethereum crypto wallets, the challenge will follow the Sign In With Ethereum (SIWE) protocol if you have toggled **SIWE Enabled** in the [SDK Configuration page](https://stytch.com/dashboard/sdk-configuration) . The domain and URI will be inferred automatically, but you may optionally override the URI. Load the challenge data by calling `cryptoWallets.authenticateStart()`. You'll then pass this challenge to the user's wallet for signing. You can do so by using the crypto provider's built-in API and by including the `crypto_wallet_address` and challenge that is provided from `cryptoWallets.authenticateStart()`. See [Ethereum's EIP-1193](https://eips.ethereum.org/EIPS/eip-1193) for an example of Ethereum's provider API.

## Parameters

<ParamField body="crypto_wallet_type" type="string" required>
  The type of wallet to authenticate. Currently ethereum and solana are supported. Wallets for any EVM-compatible chains (such as Polygon or BSC) are also supported and are grouped under the ethereum type.
</ParamField>

<ParamField body="crypto_wallet_address" type="string" required>
  The crypto wallet address to authenticate.
</ParamField>

<ParamField body="siwe_params" type="object">
  The parameters for a Sign In With Ethereum (SIWE) message. May only be passed if the crypto\_wallet\_type is ethereum and if you have toggled **SIWE Enabled** in the [Frontend SDK page](https://stytch.com/dashboard/sdk-configuration).

  <Expandable title="properties">
    <ParamField body="uri" type="string">
      Defaults to window\.location.origin. An RFC 3986 URI referring to the resource that is the subject of the signing.
    </ParamField>

    <ParamField body="statement" type="string">
      A human-readable ASCII assertion that the user will sign. The statement may only include reserved, unreserved, or space characters according to RFC 3986 definitions, and must not contain other forms of whitespace such as newlines, tabs, and carriage returns.
    </ParamField>

    <ParamField body="chain_id" type="string">
      The EIP-155 Chain ID to which the session is bound. Defaults to 1. Must be the string representation of an integer between 1 and 9,223,372,036,854,775,771, inclusive.
    </ParamField>

    <ParamField body="issued_at" type="string">
      The time when the message was generated. Defaults to the current time. All timestamps in our API conform to the RFC 3339 standard and are expressed in UTC, e.g. 2021-12-29T12:33:09Z.
    </ParamField>

    <ParamField body="not_before" type="string">
      The time when the signed authentication message will become valid. Defaults to the current time. All timestamps in our API conform to the RFC 3339 standard and are expressed in UTC, e.g. 2021-12-29T12:33:09Z.
    </ParamField>

    <ParamField body="message_request_id" type="string">
      A system-specific identifier that may be used to uniquely refer to the sign-in request. The message\_request\_id must be a valid pchar according to RFC 3986 definitions.
    </ParamField>

    <ParamField body="resources" type="array[string]">
      A list of information or references to information the user wishes to have resolved as part of authentication. Every resource must be an RFC 3986 URI.
    </ParamField>
  </Expandable>
</ParamField>

## Response

<ResponseField name="challenge" type="string">
  A challenge string to be signed by the wallet in order to prove ownership.
</ResponseField>

<ResponseField name="request_id" type="string">
  Globally unique UUID that is returned with every API call. This value is important to log for debugging purposes; we
  may ask for this value to help identify a specific API call when helping you debug an issue.
</ResponseField>

<ResponseField name="status_code" type="number">
  The HTTP status code of the response. Stytch follows standard HTTP response status code patterns, e.g. 2XX values
  equate to success, 3XX values are redirects, 4XX are client errors, and 5XX are server errors.
</ResponseField>

<Panel>
  <RequestExample>
    ```jsx theme={null}
    import { useStytch } from '@stytch/nextjs';
    import { useCallback } from 'react';

    export const Login = () => {
    const stytch = useStytch();

    const trigger = useCallback(async () => {
      /* Request user's address */
      const [crypto_wallet_address] = await ethereum.request({
        method: 'eth_requestAccounts',
      });

      /* Ask Stytch to generate a challenge for the user */
      const { challenge } = await stytch.cryptoWallets.authenticateStart({
        crypto_wallet_address,
        crypto_wallet_type: 'ethereum',
      });

      /* Ask the user to sign the challenge, this takes place on your frontend and uses the browser's built-in crypto provider API. */
      const signature = await ethereum.request({
        method: 'personal_sign',
        params: [challenge, crypto_wallet_address],
      });

      /* Send the signature back to Stytch for validation */
      await stytch.cryptoWallets.authenticate({
        crypto_wallet_address,
        crypto_wallet_type: 'ethereum',
        signature,
        session_duration_minutes: 60,
      });
    }, [stytch]);

    return <button onClick={trigger}>Sign in with Ethereum</button>;
    };
    ```
  </RequestExample>

  <ResponseExample>
    ```json 200 theme={null}
    {
      "challenge": "Signing in with Project: 7_EPetPqfdEiDCJtgad6-xsXytN3Ee9tx6mdRTQK3fC7-J2PDxpP1GAvYB9Ic4E09h-K88STiRIzKSGP",
      "request_id": "request-id-test-b05c992f-ebdc-489d-a754-c7e70ba13141"
      "status_code": 200
    }
    ```

    ```json 429 theme={null}
    {
      "status_code": 429,
      "request_id": "request-id-test-b05c992f-ebdc-489d-a754-c7e70ba13141",
      "error_type": "too_many_requests",
      "error_message": "Too many requests have been made.",
      "error_url": "https://stytch.com/docs/api/errors/429"
    }
    ```

    ```json 500 theme={null}
    {
      "status_code": 500,
      "request_id": "request-id-test-b05c992f-ebdc-489d-a754-c7e70ba13141",
      "error_type": "internal_server_error",
      "error_message": "Oops, something seems to have gone wrong, please reach out to support@stytch.com to let us know what went wrong.",
      "error_url": "https://stytch.com/docs/api/errors/500"
    }
    ```
  </ResponseExample>
</Panel>