Protecting the registration

How to send $registration activity to Castle and use the response to prevent bad actors from signing up for new accounts.

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Make sure you've first integrated the client-side integration in order to generate the "request tokens" required for each call to the Risk and Filter API.

The registration activity is sent to Castle whenever a user registers for an account on your platform. It doesn't necessarily mean that the user onboarding process is completed, but at least that the user account was created.

The inline response from the Risk endpoint can be used to detect and fake accounts, or trigger additional verification when too many behavioral trigger.

How to add the $registration activity:

  1. A user submits a form with desired account information, e.g. name, email and password
  2. The email (or other identifier) is checked against the user database for whether it already exists or not.
  3. If the account doesn't exist, create the account record as you normally would and send $registration with $succeeded status.
  4. If the user already exists, send $registration with $failed status.
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Where in the registration flow to send the different statuses

Sending successful registration activity

Use the Risk API to send information about the user at the time of account creation.

:notebook-with-decorative-cover: You will need to generate and forward the request_token string from your frontend by using the Browser SDK or a Mobile SDK.

castle = ::Castle::Client.new

begin
  # see https://docs.castle.io/docs/a-full-integration#client-side-integration
  token = request.params['castle_request_token']
  
  # extract a sanitized list HTTP headers and IP address
  context = Castle::Context::Prepare.call(request)

  res = castle.risk(
    request_token: token,
    type: '$registration',
    status: '$succeeded',
    user: {
      id: 'ca1242f498', # Required. A unique, persistent user identifier
      registered_at: '2012-12-02T00:30:08.276Z', # Recommended
      email: '[email protected]', # Recommended
      phone: '+1415232183', # Optional. E.164 format
      name: 'Mike Gray', # Optional
      address: { # Optional
        line1: "200 Fell St",
        line2: "Apt 1028",
        city: "San Francisco",
        region_code: "CA",
        country_code: "US" # Required. ISO-3166 country code
      },
      traits: { # Custom user data for visualization purposes
        nationality: 'US',
        birth_date: '1976-02-02'
      }
    },
    authentication_method: { # Optional. See link below
      type: '$password' # The most common type
    },
    context: {
      ip: context[:ip],
      headers: context[:headers]
    },
    properties: { # Custom event data for visualization purposes
      solved_captcha: true,
      attempts: 3
    }
  )

  if res[:risk] > 0.9
    # IMPLEMENT: Deny attempt
  end
  
rescue Castle::InvalidRequestTokenError
  # Deny attempt. Likely a bad actor bypassing fingerprinting
rescue Castle::Error => e
  # Allow attempt. Data missing or invalid, or a server or timeout error
end
// NOTE: See the Ruby example for a more comprehensive set of parameters

try {
  $token = $_POST['castle_request_token'];

  $res = Castle::risk([
    'type' => '$registration',
    'status' => '$succeeded',
    'request_token' => $token,
    'user' => [
      'id' => $user->id,
      'email' => $user->email
    ],
    'context' => [
      'ip' => Castle_RequestContext::extractIp(),
      'headers' => Castle_RequestContext::extractHeaders()
    ]
  ]);

  if ($res->risk > 0.9) {
    // IMPLEMENT: Deny attempt
  }

} catch (Castle_InvalidRequestTokenError $e) {
  // Deny attempt. Likely a bad actor bypassing fingerprinting
} catch (Castle_Error $e) {
  // Allow attempt. Data missing or invalid, or a server or timeout error
}
# NOTE: See the Ruby example for a more comprehensive set of parameters

try:
    token = request.form['castle_request_token'] # Using Flask
    context = ContextPrepare.call(request)

    client = Client()

    res = client.risk({
        'type': '$registration',
        'status': '$succeeded',
        'request_token': token,
        'user': {
            'id': user.id,
            'email': user.email
        },
        'context': {
          'ip': context['ip'],
          'headers': context['headers']
        }
    })

    if res['risk'] > 0.9:
        # IMPLEMENT: Deny attempt

except InvalidRequestTokenError:
    # Deny attempt. Likely a bad actor bypassing fingerprinting
except CastleError as e:
    # Allow attempt. Data missing or invalid, or a server or timeout error
// NOTE: See the Ruby example for a more comprehensive set of parameters

String token = request.getParameter("castle_request_token");

Castle castle = Castle.initialize();
CastleContextBuilder context = castle.contextBuilder().fromHttpServletRequest(request)

try {
  CastleResponse response = castle.client().risk(ImmutableMap.builder()
    .put("type", "$registration")
    .put("status", "$succeeded")
    .put(Castle.KEY_CONTEXT, ImmutableMap.builder()
      .put(Castle.KEY_IP, context.getIp())
      .put(Castle.KEY_HEADERS, context.getHeaders())
      build()
    )
    .put(Castle.KEY_USER, ImmutableMap.builder()
      .put("id", user.getId())
      .put("email", user.getEmail())
      .build()
    )
    .put(Castle.KEY_REQUEST_TOKEN, token)
    .build()
  );
  
  float risk = response.json().getAsJsonObject().get("risk").getAsFloat();

  if (risk > 0.9) {
    // IMPLEMENT: Deny attempt
  };
  
} catch (CastleApiInvalidRequestTokenException requestTokenException) {
    // IMPLEMENT: Deny attempt. Likely a bad actor
} catch (CastleRuntimeException runtimeException) {
    // Data missing or invalid. Needs to be fixed
}
// NOTE: See the Ruby example for a more comprehensive set of parameters

try {
  var token = request.body["castle_request_token"]; // Using Express

  const castle = new Castle({ apiSecret: 'YOUR SECRET HERE' });
  const context = ContextPrepareService.call(request, {}, castle.configuration);

  const res = castle.risk({
    type: '$registration',
    status: '$succeeded',
    request_token: token,
    user: {
      id: user.id,
      email: user.email
    },
    context: {
      ip: context.ip,
      headers: context.headers
    }
  });

  if (res.risk > 0.9) {
    // IMPLEMENT: Deny attempt
  }
} catch (e) {
  if (e instanceof InvalidRequestTokenError) {
     // IMPLEMENT: Deny attempt. Likely a bad actor
  } else if (e instanceof APIError) {
     // Allow attempt. Data missing or invalid, or a server or timeout error
  }
}

:notebook-with-decorative-cover: See the documentation for authentication_method to see all the available options, such as how to specify account creation with an email or SMS magic link.

Taking action

The response from the call to the Risk API can then be used to take the appropriate action:

  • As a starting point, we recommend putting the newly created account through additional verification whenever the risk score is above 0.9. If the user fails to successfully complete the additional verification within a desired timeframe, you should delete the account, as it will otherwise just occupy unnecessary space in your database as well as potentially skew your product metrics.
  • The stricter recommendation is to prompt the user for additional verification when then risk score is above 0.6, and for responses with a score of 0.9 and above, drop the request and mark the account for deletion.

Sending failed registration activity

The Filter API is used for sending anonymous user activity, such as a failed registration attempt. Instead of passing the email or phone in the user object, you'll pass the form parameters in the params object, where email and phone are the only supported fields. If you're doing lookups in your app based on the user-submitted email or phone, you can pass the matching user identifier as matching_user_id which will resolve any existing user in the resulting event.

castle = ::Castle::Client.new

begin
  token = request.params['castle_request_token']
  context = Castle::Context::Prepare.call(request)

  res = castle.filter(
    type: '$registration',
    status: '$failed',
    matching_user_id: 'ca1242f498', # Optional
    params: {
      email: request.params['email']
    },
    request_token: token,
    context: {
      ip: context[:ip],
      headers: context[:headers]
    }
  )
  
rescue Castle::InvalidRequestTokenError
  # Deny attempt. Likely a bad actor bypassing fingerprinting
rescue Castle::Error => e
  # Allow attempt. Data missing or invalid, or a server or timeout error
end
try {
  $token = $_POST['castle_request_token'];

  $res = Castle::filter([
    'type' => '$registration',
    'status' => 'failed',
    'matching_user_id' => 'ca1242f498', // Optional
    'params' => [
      'email' => $_POST['email']
    ]
    'request_token' => $token,
    'context' => [
      'ip' => Castle_RequestContext::extractIp(),
      'headers' => Castle_RequestContext::extractHeaders()
    ]
  ]);

} catch (Castle_InvalidRequestTokenError $e) {
  // Deny attempt. Likely a bad actor bypassing fingerprinting
} catch (Castle_Error $e) {
  // Allow attempt. Data missing or invalid, or a server or timeout error
}
try:
    token = request.form['castle_request_token'] # Using Flask
    context = ContextPrepare.call(request)

    client = Client()

    res = client.filter({
        'type': '$registration',
        'status': '$failed',
        'matching_user_id': 'ca1242f498', # Optional
        'params': {
          'email': request.form['email']
        }
        'request_token': token,
        'context': {
          'ip': context['ip'],
          'headers': context['headers']
        }
    })
    
except InvalidRequestTokenError:
    # Deny attempt. Likely a bad actor bypassing fingerprinting
except CastleError as e:
    # Allow attempt. Data missing or invalid, or a server or timeout error
String token = request.getParameter("castle_request_token");

Castle castle = Castle.initialize();
CastleContextBuilder context = castle.contextBuilder().fromHttpServletRequest(request)

try {
  CastleResponse response = castle.client().filter(ImmutableMap.builder()
    .put("type" "$registration")
    .put("status", "$failed")
    .put(Castle.KEY_CONTEXT, ImmutableMap.builder()
      .put(Castle.KEY_IP, context.getIp())
      .put(Castle.KEY_HEADERS, context.getHeaders())
      build()
    )
    .put("matching_user_id", "ca1242f498") // Optional
    .put("params", ImmutableMap.builder()
      .put("email", request.getParameter("email"))
      .build()
    .put(Castle.KEY_REQUEST_TOKEN, token)
    .build()
  );
} catch (CastleApiInvalidRequestTokenException requestTokenException) {
    // IMPLEMENT: Deny attempt. Likely a bad actor
} catch (CastleRuntimeException runtimeException) {
    // Data missing or invalid. Needs to be fixed
}
try {
  var token = request.body["castle_request_token"]; // Using Express

  const castle = new Castle({ apiSecret: 'YOUR SECRET HERE' });
  const context = ContextPrepareService.call(request, {}, castle.configuration);

  const res = castle.filter({
    type: '$registration',
    status: '$failed',
    request_token: token,
    matching_user_id: 'ca1242f498', // Optional
    params: {
      email: request.body["email"]
    },
    context: {
      ip: context.ip,
      headers: context.headers
    }
  });
} catch (e) {
  if (e instanceof InvalidRequestTokenError) {
     // IMPLEMENT: Deny attempt. Likely a bad actor
  } else if (e instanceof APIError) {
     // Allow attempt. Data missing or invalid, or a server or timeout error
  }
}

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