# Sign Message

The "Sign Message" feature in the KrypC wallet-dev Service API allows users to generate cryptographic signatures for messages, providing a secure way to verify ownership or authorization in decentralized applications. This feature is useful for identity verification and message authentication in blockchain and cryptographic systems.

This will allow to Sign message.

## API Specification

## Sign Message API

<mark style="color:green;">`POST`</mark> `https://api.krypcore.com/api/v0/devWallet/signMessage`

To sign message API under the given instance.&#x20;

#### Headers

| Name                                            | Type   | Description            |
| ----------------------------------------------- | ------ | ---------------------- |
| DappId<mark style="color:red;">\*</mark>        | String | DappId                 |
| Authorization<mark style="color:red;">\*</mark> | String | User Auth key obtained |
| SubscriptionId                                  | String | SubscriptionId         |
| ChainId                                         | String | ChainId                |

#### Request Body

| Name                                         | Type   | Description |
| -------------------------------------------- | ------ | ----------- |
| privateKey<mark style="color:red;">\*</mark> | String | Private Key |
| message<mark style="color:red;">\*</mark>    | String | Message     |

{% tabs %}
{% tab title="200: OK SUCCESS" %}

```javascript
{
    "Data": {
        "signature": "0x1b5ef0f705318b13cd25e46492897c3d59058334bca7931cd6e01a3a4f9a374671bb93c34e926ffd3c1326be91beda6bc5ecec2813a9bc75ebae4df6a24ac69901"
    },
    "Message": "Signed message successfully",
    "Status": "SUCCESS"
}
```

{% endtab %}

{% tab title="401: Unauthorized Failure in authentication" %}

```javascript
{
    "message": "Invalid API key in request"
}
```

{% endtab %}

{% tab title="500: Internal Server Error Key values should be given" %}

```
{
    "message": "Internal Server Error"
}
```

{% endtab %}
{% endtabs %}

Take a look at how you might call this method using our official libraries, or via `curl`

{% tabs %}
{% tab title="curl" %}

```bash

curl --location 'https://api.krypcore.com/api/v0/devWallet/signMessage' \
--header 'DappId: **********' \
--header 'Authorization: **********' \
--header 'SubscriptionId: ********' \
--header 'ChainId: ********' \
--header 'Content-Type: application/json' \
--data '{
    "privateKey": "**********",
    "message":"Hello"
}'
```

{% endtab %}

{% tab title="Node.js (Fetch)" %}

```javascript

var myHeaders = new Headers();
myHeaders.append("DappId", "**********");
myHeaders.append("Authorization", "**********");
myHeaders.append("SubscriptionId", "********");
myHeaders.append("ChainId", "********");
myHeaders.append("Content-Type", "application/json");

var raw = JSON.stringify({
  "privateKey": "**********",
  "message": "Hello"
});

var requestOptions = {
  method: 'POST',
  headers: myHeaders,
  body: raw,
  redirect: 'follow'
};

fetch("https://api.krypcore.com/api/v0/devWallet/signMessage", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));
```

{% endtab %}

{% tab title="Python " %}

```python

import requests
import json

url = "https://api.krypcore.com/api/v0/devWallet/signMessage"

payload = json.dumps({
  "privateKey": "**********",
  "message": "Hello"
})
headers = {
  'DappId': '**********',
  'Authorization': '**********',
  'SubscriptionId': '********',
  'ChainId': '********',
  'Content-Type': 'application/json'
}

response = requests.request("POST", url, headers=headers, data=payload)

print(response.text)

```

{% endtab %}

{% tab title="Golang" %}

```go

package main

import (
  "fmt"
  "strings"
  "net/http"
  "io/ioutil"
)

func main() {

  url := "https://api.krypcore.com/api/v0/devWallet/signMessage"
  method := "POST"

  payload := strings.NewReader(`{
    "privateKey": "**********",
    "message":"Hello"
}`)

  client := &http.Client {
  }
  req, err := http.NewRequest(method, url, payload)

  if err != nil {
    fmt.Println(err)
    return
  }
  req.Header.Add("DappId", "**********")
  req.Header.Add("Authorization", "**********")
  req.Header.Add("SubscriptionId", "********")
  req.Header.Add("ChainId", "********")
  req.Header.Add("Content-Type", "application/json")

  res, err := client.Do(req)
  if err != nil {
    fmt.Println(err)
    return
  }
  defer res.Body.Close()

  body, err := ioutil.ReadAll(res.Body)
  if err != nil {
    fmt.Println(err)
    return
  }
  fmt.Println(string(body))
}
```

{% endtab %}
{% endtabs %}