curl --request POST \
  --url https://api.lightspark.com/grid/2025-10-13/customers/external-accounts/{externalAccountId}/challenge \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "method": "WALLET_SIGNATURE"
}
'

import LightsparkGrid from '@lightsparkdev/grid';

const client = new LightsparkGrid({
  username: process.env['GRID_CLIENT_ID'], // This is the default and can be omitted
  password: process.env['GRID_CLIENT_SECRET'], // This is the default and can be omitted
});

const ownershipChallenge = await client.customers.externalAccounts.challenge('externalAccountId', {
  method: 'WALLET_SIGNATURE',
});

console.log(ownershipChallenge);

package com.lightspark.grid.example

import com.lightspark.grid.client.LightsparkGridClient
import com.lightspark.grid.client.okhttp.LightsparkGridOkHttpClient
import com.lightspark.grid.models.customers.externalaccounts.ExternalAccountChallengeParams
import com.lightspark.grid.models.customers.externalaccounts.OwnershipChallenge
import com.lightspark.grid.models.customers.externalaccounts.OwnershipChallengeRequest
import com.lightspark.grid.models.customers.externalaccounts.OwnershipVerificationMethod

fun main() {
    val client: LightsparkGridClient = LightsparkGridOkHttpClient.fromEnv()

    val params: ExternalAccountChallengeParams = ExternalAccountChallengeParams.builder()
        .externalAccountId("externalAccountId")
        .ownershipChallengeRequest(OwnershipChallengeRequest.builder()
            .method(OwnershipVerificationMethod.WALLET_SIGNATURE)
            .build())
        .build()
    val ownershipChallenge: OwnershipChallenge = client.customers().externalAccounts().challenge(params)
}

{
  "method": "WALLET_SIGNATURE",
  "messageToSign": "I verify that I control this wallet. Nonce: 019542f5-b3e7-1d02",
  "expiresAt": "2025-08-15T15:32:00Z"
}

{
  "status": 400,
  "message": "<string>",
  "details": {
    "errors": [
      {
        "field": "identifier",
        "constraint": {
          "format": "email",
          "pattern": "^\\d{5}(-\\d{4})?$",
          "enum": [
            "SSN",
            "ITIN",
            "NON_US_TAX_ID"
          ],
          "minLength": 1,
          "maxLength": 500
        },
        "message": "Value is not one of the allowed enum members."
      }
    ]
  }
}

{
  "status": 401,
  "message": "<string>",
  "details": {}
}

{
  "status": 404,
  "message": "<string>",
  "details": {}
}

{
  "status": 409,
  "message": "<string>",
  "details": {}
}

{
  "status": 500,
  "message": "<string>",
  "details": {}
}