Sign In with Device

Our JavaScript SDK offers the easiest way to add "Sign in with device" into your website. You can simply call a function and it does most of the heavy lifting and authentication for you.

Concepts: Learn about how Sign in with Device works.

There are major updates planned for this feature. Contact us in Slack so we can help you prepare for it.

Overview

Authenticating users using Trusted Devices with Cotter's JavaScript SDK consists of the following steps:

Embed Cotter in your website
Receive a Callback with user's authentication event and a token from Cotter
Validate the token and proceed with logins or transactions.

Keep in mind that this works if you have a companion app that allows users to register their device as a Trusted Device.

What you're building

There are 2 ways to present Cotter's authentication prompt from your website:

In the Login form: after entering their email/phone number, if there's a trusted device, it will automatically prompt the user to approve the login from their device.
As a popup: When a user triggers an action that requires authentication, like doing a transaction or opening sensitive information, you can open a popup that will ask the user to approve the transaction from their device.

In both cases, you will receive an Event Response (the same event response that you'll receive in mobile app) that you can pass in your backend server during the login/transaction function and check if the user has authenticated and approved the event.

Required Steps

Step 1: Setting Authentication Methods

You need to set allowed methods for authenticating your users. To allow TRUSTED DEVICES (and OTP if you want to allow it as a fallback method), go to https://dev.cotter.app/rules

Remember to set the correct Project in the dropdown list

We will cover the Login Form here, and the Pop Up in the next guide.

Setup Cotter with your API_KEY_ID and some config
Show Cotter form
Receive a Callback in your OnSuccess function the authentication event and a signature from Cotter in your backend server

Step 1: Setup Cotter

Include Javascript SDK

To use our Javascript SDK, include the script below in your HTML page.

<script src="https://js.cotter.app/lib/cotter.js" type="text/javascript"></script>

Initialize Cotter

Initialize Cotter in your HTML page, below the script you imported above. For React apps, initialize this in index.html. You can use it later in any of your pages.

<script>
  var cotter = new CotterLogin(config);
</script>

Configuration

Here's a basic configuration example:

var config = {
  ApiKeyID: "<your-API-KEY-ID>",
  
  // Type of identity your want to collect: EMAIL or PHONE
  Type: "PHONE",
  
  // div id of the container for Cotter Form
  ContainerID: "cotter-container-login",
  SkipRedirectURL: true,
  
  // the JSON key for the phone number or email to be posted to RedirectURL
  // Read more on RedirectURL JSON Object below
  IdentifierField: "phone",
  
  // OnBegin here is MANDATORY
  // You need to return the Cotter User ID. (If you used client_user_id, 
  // use that instead).
  OnBegin: async payload => {      
    var { userID, err } = await getUserIDFromIdentifier(
      payload.identifier
    );
    return {
      userID: userID,
      err: err
    };
  },
  
  // After the user successfully logged-in, the SDK will return a payload
  // about the login request into this OnSuccess function.
  OnSuccess: payload => {
    console.log(payload)
  },
  
  // (optional) Allow login using OTP sent to email or phone number
  // if user doesn't have Trusted Device set up
  // or if user choose to use OTP instead of trusted device
  // (To enable this, you have to set OTP true in the dashboard)
  AllowOTPFallback: true,
};

// Getting the User ID usnig Cotter's API
const getUserIDFromIdentifier = async (identifier) => {
  try {
    const resp = await fetch(
      `https://www.cotter.app/api/v0/user?identifier=${encodeURIComponent(
        identifier
      )}`,
      { headers: { API_KEY_ID: apiKey } }
    );
    const respJSON = await resp.json();
    const nullUUID = "00000000-0000-0000-0000-000000000000";
    return {
      userID: respJSON.ID === nullUUID ? null : respJSON.client_user_id,
      err: respJSON.ID === nullUUID ? "User not found" : null
    };
  } catch (e) {
    return {
      userID: null,
      err: e.message
    };
  }
};

Advanced Customization

Check out how you can customize the form and change the configuration.

Step 2: Show Cotter Form

To show the cotter form,

1. Add the <div> container.

Put a <div> with the id you specified above as ContainerID inside your page. For example, if your "ContainerID": "cotter-container-login", put this in your html:

<div
  id="cotter-container-login"
  style="width: 300px; height: 300px;"
></div>

2. Show the form

<script>
  cotter.showForm();
</script>

What we have so far

index.html

<script
  src="https://js.cotter.app/lib/cotter.js"
  type="text/javascript"
></script>

<div id="cotter-container-login" style="width: 300px; height: 300px;"></div>

<script>
  var config = {
    ApiKeyID: "API_KEY_ID",
    SkipRedirectURL: true,
    Type: "PHONE", // EMAIL or PHONE
    ContainerID: "cotter-container-login",
    IdentifierField: "phone",
    OnSuccess: payload => {
      console.log(payload)
    },
    AllowOTPFallback: true,
    OnBegin: async payload => {      
      var { userID, err } = await getUserIDFromIdentifier(
        payload.identifier
      );
      return {
        userID: userID,
        err: err
      };
    },
  };
  var cotter = new CotterLogin(config);
  cotter.showForm();
  
  
  // Getting the User ID usnig Cotter's API
  const getUserIDFromIdentifier = async (identifier) => {
    try {
      const resp = await fetch(
        `https://www.cotter.app/api/v0/user?identifier=${encodeURIComponent(
          identifier
        )}`,
        { headers: { API_KEY_ID: apiKey } }
      );
      const respJSON = await resp.json();
      const nullUUID = "00000000-0000-0000-0000-000000000000";
      return {
        userID: respJSON.ID === nullUUID ? null : respJSON.client_user_id,
        err: respJSON.ID === nullUUID ? "User not found" : null
      };
    } catch (e) {
      return {
        userID: null,
        err: e.message
      };
    }
  };
</script>

Step 3: Receive the Response in your OnSuccess function

We will send a JSON Object describing the Authentication Event to your OnSuccess function. The JSON Object will have the following format:

{
  "ID": 2397,
  "CreatedAt": "2020-04-01T05:28:12.540127Z",
  "UpdatedAt": "2020-04-01T05:28:16.599833Z",
  "DeletedAt": null,
  "client_user_id": "<YOUR USER ID>",
  "issuer": "<YOUR API KEY ID>",
  "event": "LOGIN_WEB",
  "ip": "123.347.26.236",
  "location": "San Mateo",
  "timestamp": "1585718892",
  "method": "TRUSTED_DEVICE",
  "new": false,
  "approved": true,
  "signature": "reBafVsmpxO7km5jpRQ3xA..."
}