# Sign-In Message

> Coming soon, upon request — this feature is turned on for your tenant by the Aurea team. [Contact us](https://www.aureahub.com/contact)

The message the user's wallet signs to open its card program session, built by Aurea with a fresh nonce: step 1 of the session ([Cards & EUR Account](https://docs.aureahub.com/docs/guide-cards.md) › The Card Program Session).

## Overview

- `address`: the EVM wallet the user signs in with, in any case. The message names it in lower case, as `address` in the answer.
- `message` is the Sign-In with Ethereum (EIP-4361) message to sign, lines separated by `\n`: sign it exactly as answered, never rebuild it. `messageHex` is the same bytes as `0x` hex, for [Sign Personal Message](https://docs.aureahub.com/docs/dapps-sign.md). `nonce` and `issuedAt` are what it carries.
- Then [Sign In](https://docs.aureahub.com/docs/cards-auth-challenge.md) with `message`, its `signature` and `address`, within a few minutes. Nothing is stored by this call.
- [Coming soon, upon request](https://docs.aureahub.com/docs/feature-availability.md) `403` until cards are on for your tenant; `400` until your tenant's card program access is set up, or for an `address` that is not `0x` and 40 hex characters. `503` `CARD_PROGRAM_NONCE_UNAVAILABLE` when the card program gave no nonce: retry shortly.

## Endpoint

### `GET /v1/gnosis/auth/sign-in-message`

Authentication: bearer token required.

The card program's sign-in message for the wallet, with a fresh nonce, ready to sign.

**Query parameters**

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `address` | string | yes | The EVM address the user signs in with |

**Responses**

`200` OK

```json
{
  "message": "aureahub.com wants you to sign in with your Ethereum account:\n0x2f4b6c2e9a1d5f3b7c8e0a4d6b2c9e1f3a5d7b90\n\n…\nNonce: Kq3f0uT7xLmB9pZr\nIssued At: 2026-10-14T09:00:00.000Z",
  "messageHex": "0x617572656168…",
  "address": "0x2f4b6c2e9a1d5f3b7c8e0a4d6b2c9e1f3a5d7b90",
  "nonce": "Kq3f0uT7xLmB9pZr",
  "issuedAt": "2026-10-14T09:00:00.000Z"
}
```

`503` No Nonce

```json
{
  "statusCode": 503,
  "error": "ServiceUnavailableError",
  "message": "The card program did not answer a sign-in nonce. Try again in a moment; if it keeps failing, write to help@aureahub.com.",
  "details": { "code": "CARD_PROGRAM_NONCE_UNAVAILABLE" }
}
```

**Example request**

```bash
curl "https://api.aureahub.com/v1/gnosis/auth/sign-in-message?address=0x2f4b6c2e9a1d5f3b7c8e0a4d6b2c9e1f3a5d7b90" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"
```

---

Web version: https://docs.aureahub.com/#cards-auth-message