# DID

### Step 1. Check if the address has a DID.

```cpp
DidListResponse getResponse = request.getDidList(node,address);
```

Parameters：

| Name    | Type   | Description    | Required |
| ------- | ------ | -------------- | -------- |
| node    | string | edge node url  | true     |
| address | string | wallet address | True     |

Returns：

`DidListResponse`:

| Name  | Type         | Description      | Required |
| ----- | ------------ | ---------------- | -------- |
| Array | string array | a list of DID(s) | true     |

### Step 2. Choose DID or log in with an wallet address

Use the address for login when the interface array is empty; otherwise, use the first element of the array as the DID parameter.

```cpp
PreloginResponse postResponse = request.prelogin(node, preloginRequest.toString());
```

Parameters:

| Name    | Type   | Description                    | Required |
| ------- | ------ | ------------------------------ | -------- |
| did     | string | DID string，DID or address      | False    |
| address | string | wallet address, DID or address | False    |
| node    | string | edge node url                  | True     |

Returns:

`PreloginResponse`:

| Name    | Type   | Description                    | Required |
| ------- | ------ | ------------------------------ | -------- |
| did     | string | DID (existed or newly created) | true     |
| message | string | message to be signed           | true     |
| updated | string | update time                    | true     |

### 3. Sign the return value in step 2.

```cpp
LoginResponse loginResponse = request.didlogin(node, loginRequest.toString());
```

Parameters:

`LoginRequest`:

| Name        | Type            | Description                                         | Required |
| ----------- | --------------- | --------------------------------------------------- | -------- |
| type        | string          | login type（current value is `m.login.did.identity`） | true     |
| updated     | string          | time returned by `pre_login` `updated`              | true     |
| identifier  | IdentifierModel | login information                                   | true     |
| `device_id` | string          | device id, not required for new device              | false    |

`IdentifierModel` type：

| Name  | Type   | Description                                                                                                                                                                                            |
| ----- | ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| did   | string | DID                                                                                                                                                                                                    |
| token | string | sign the returned message from `pre_login`, and encode with *base16*. The signing method is to sign directly using a private key: You can directly call the `web3Sign()` in the DID class for signing. |

Returns:

`LoginResponse`:

| Name          | Type   | Description  | Required |
| ------------- | ------ | ------------ | -------- |
| access\_token | string | access token | true     |
| user\_id      | string | user id      | true     |
| device\_id    | string | device id    | true     |


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