Enroll and Challenge Email Authenticators

Auth0 provides a built-in MFA enrollment and authentication flow using Universal Login. However, if you want to create your own user interface, you can use the MFA API to accomplish it.

When email is enabled as a factor, all users with verified emails will be able to use them to complete MFA.

Availability varies by Auth0 plan and login method

Both the login implementation you use and your Auth0 plan or custom agreement affect whether this feature is available. To learn more, read Universal Login vs. Classic Login and Pricing.

Prerequisites

Before you can use the MFA APIs, you'll need to enable the MFA grant type for your application. Go to Auth0 Dashboard > Applications > Advanced Settings > Grant Types and select MFA.

Configure Email as a factor in the Dashboard or using the Management API.

Enroll with email

To enable users to enroll emails in addition to their verified email in their primary identity, you need to complete the following steps.

Get MFA token

Depending on when you are triggering enrollment, you can obtain an access token for using the MFA API in different ways:

If you are enrolling during authentication, see Authenticate With Resource Owner Password Grant and MFA.
If you want to let the user enroll a factor at any moment, see Manage MFA Factor Enrollments.

Enroll authenticator

Make a POST request to the MFA Associate endpoint to enroll the user's authenticator. The bearer token required by this endpoint is the MFA token obtained in the previous step.

Use the following parameters:

Parameter	Value
`authentication_types`	`[oob]`
`oob_channels`	`[email]`
`email`	`email@address.com`, the users email address.

cURL
C#
Go
Java
Node.JS
Obj-C
...
- PHP
- Python
- Ruby
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curl --request POST \
  --url 'https://{yourDomain}/mfa/associate' \
  --header 'authorization: Bearer MFA_TOKEN' \
  --data '{ "authenticator_types": ["oob"], "oob_channels": ["email"], "email" : "email@address.com" }'

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var client = new RestClient("https://{yourDomain}/mfa/associate");
var request = new RestRequest(Method.POST);
request.AddHeader("authorization", "Bearer MFA_TOKEN");
request.AddParameter("undefined", "{ \"authenticator_types\": [\"oob\"], \"oob_channels\": [\"email\"], \"email\" : \"email@address.com\" }", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

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package main

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

func main() {

	url := "https://{yourDomain}/mfa/associate"

	payload := strings.NewReader("{ \"authenticator_types\": [\"oob\"], \"oob_channels\": [\"email\"], \"email\" : \"email@address.com\" }")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("authorization", "Bearer MFA_TOKEN")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := ioutil.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}

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HttpResponse<String> response = Unirest.post("https://{yourDomain}/mfa/associate")
  .header("authorization", "Bearer MFA_TOKEN")
  .body("{ \"authenticator_types\": [\"oob\"], \"oob_channels\": [\"email\"], \"email\" : \"email@address.com\" }")
  .asString();

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var axios = require("axios").default;

var options = {
  method: 'POST',
  url: 'https://{yourDomain}/mfa/associate',
  headers: {authorization: 'Bearer MFA_TOKEN'},
  data: {
    authenticator_types: ['oob'],
    oob_channels: ['email'],
    email: 'email@address.com'
  }
};

axios.request(options).then(function (response) {
  console.log(response.data);
}).catch(function (error) {
  console.error(error);
});

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#import <Foundation/Foundation.h>

NSDictionary *headers = @{ @"authorization": @"Bearer MFA_TOKEN" };
NSDictionary *parameters = @{ @"authenticator_types": @[ @"oob" ],
                              @"oob_channels": @[ @"email" ],
                              @"email": @"email@address.com" };

NSData *postData = [NSJSONSerialization dataWithJSONObject:parameters options:0 error:nil];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/mfa/associate"]
                                                       cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:10.0];
[request setHTTPMethod:@"POST"];
[request setAllHTTPHeaderFields:headers];
[request setHTTPBody:postData];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                if (error) {
                                                    NSLog(@"%@", error);
                                                } else {
                                                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                    NSLog(@"%@", httpResponse);
                                                }
                                            }];
[dataTask resume];

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$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{yourDomain}/mfa/associate",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "{ \"authenticator_types\": [\"oob\"], \"oob_channels\": [\"email\"], \"email\" : \"email@address.com\" }",
  CURLOPT_HTTPHEADER => [
    "authorization: Bearer MFA_TOKEN"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

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import http.client

conn = http.client.HTTPSConnection("")

payload = "{ \"authenticator_types\": [\"oob\"], \"oob_channels\": [\"email\"], \"email\" : \"email@address.com\" }"

headers = { 'authorization': "Bearer MFA_TOKEN" }

conn.request("POST", "/{yourDomain}/mfa/associate", payload, headers)

res = conn.getresponse()
data = res.read()

print(data.decode("utf-8"))

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require 'uri'
require 'net/http'
require 'openssl'

url = URI("https://{yourDomain}/mfa/associate")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE

request = Net::HTTP::Post.new(url)
request["authorization"] = 'Bearer MFA_TOKEN'
request.body = "{ \"authenticator_types\": [\"oob\"], \"oob_channels\": [\"email\"], \"email\" : \"email@address.com\" }"

response = http.request(request)
puts response.read_body

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import Foundation

let headers = ["authorization": "Bearer MFA_TOKEN"]
let parameters = [
  "authenticator_types": ["oob"],
  "oob_channels": ["email"],
  "email": "email@address.com"
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/mfa/associate")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()

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If successful, you receive a response like this:

{
    "authenticator_type": "oob",
    "binding_method": "prompt",
    "oob_code" : "Fe26..nWE",
    "oob_channel": "email",
    "recovery_codes": [ "N3BGPZZWJ85JLCNPZBDW6QXC" ]
  }

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If you get a User is already enrolled error, the user already has an MFA factor enrolled. Before associating another factor with the user, you must challenge the user with the existing factor.

If this is the first time the user is associating an authenticator, you'll notice the response includes recovery_codes. Recovery codes are used to access the user's account in the event that they lose access to the account or device used for their second-factor authentication. These are one-time usable codes, and new ones are generated as necessary.

Confirm email enrollment

The user should receive an email containing the 6-digit code that they can provide to the application.

To complete the enrollment, make a POST request to the /oath/token endpoint. Include the oob_code returned in the previous response and the binding_code with the value in the email message.

cURL
C#
Go
Java
Node.JS
Obj-C
...
- PHP
- Python
- Ruby
- Swift

curl --request POST \
  --url 'https://{yourDomain}/oauth/token' \
  --data grant_type=http://auth0.com/oauth/grant-type/mfa-oob \
  --data 'mfa_token={mfaToken}' \
  --data 'oob_code={oobCode}' \
  --data 'binding_code={userEmailOtpCode}' \
  --data 'client_id={yourClientId}' \
  --data 'client_secret={yourClientSecret}'

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var client = new RestClient("https://{yourDomain}/oauth/token");
var request = new RestRequest(Method.POST);
request.AddParameter("undefined", "grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fmfa-oob&mfa_token=%7BmfaToken%7D&oob_code=%7BoobCode%7D&binding_code=%7BuserEmailOtpCode%7D&client_id={yourClientId}&client_secret=%7ByourClientSecret%7D", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

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package main

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

func main() {

	url := "https://{yourDomain}/oauth/token"

	payload := strings.NewReader("grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fmfa-oob&mfa_token=%7BmfaToken%7D&oob_code=%7BoobCode%7D&binding_code=%7BuserEmailOtpCode%7D&client_id={yourClientId}&client_secret=%7ByourClientSecret%7D")

	req, _ := http.NewRequest("POST", url, payload)

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := ioutil.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}

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HttpResponse<String> response = Unirest.post("https://{yourDomain}/oauth/token")
  .body("grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fmfa-oob&mfa_token=%7BmfaToken%7D&oob_code=%7BoobCode%7D&binding_code=%7BuserEmailOtpCode%7D&client_id={yourClientId}&client_secret=%7ByourClientSecret%7D")
  .asString();

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var axios = require("axios").default;

var options = {
  method: 'POST',
  url: 'https://{yourDomain}/oauth/token',
  data: new URLSearchParams({
    grant_type: 'http://auth0.com/oauth/grant-type/mfa-oob',
    mfa_token: '{mfaToken}',
    oob_code: '{oobCode}',
    binding_code: '{userEmailOtpCode}',
    client_id: '{yourClientId}',
    client_secret: '{yourClientSecret}'
  })
};

axios.request(options).then(function (response) {
  console.log(response.data);
}).catch(function (error) {
  console.error(error);
});

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#import <Foundation/Foundation.h>

NSMutableData *postData = [[NSMutableData alloc] initWithData:[@"grant_type=http://auth0.com/oauth/grant-type/mfa-oob" dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[@"&mfa_token={mfaToken}" dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[@"&oob_code={oobCode}" dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[@"&binding_code={userEmailOtpCode}" dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[@"&client_id={yourClientId}" dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[@"&client_secret={yourClientSecret}" dataUsingEncoding:NSUTF8StringEncoding]];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/oauth/token"]
                                                       cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:10.0];
[request setHTTPMethod:@"POST"];
[request setHTTPBody:postData];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                if (error) {
                                                    NSLog(@"%@", error);
                                                } else {
                                                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                    NSLog(@"%@", httpResponse);
                                                }
                                            }];
[dataTask resume];

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$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{yourDomain}/oauth/token",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fmfa-oob&mfa_token=%7BmfaToken%7D&oob_code=%7BoobCode%7D&binding_code=%7BuserEmailOtpCode%7D&client_id={yourClientId}&client_secret=%7ByourClientSecret%7D",
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

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import http.client

conn = http.client.HTTPSConnection("")

payload = "grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fmfa-oob&mfa_token=%7BmfaToken%7D&oob_code=%7BoobCode%7D&binding_code=%7BuserEmailOtpCode%7D&client_id={yourClientId}&client_secret=%7ByourClientSecret%7D"

conn.request("POST", "/{yourDomain}/oauth/token", payload)

res = conn.getresponse()
data = res.read()

print(data.decode("utf-8"))

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require 'uri'
require 'net/http'
require 'openssl'

url = URI("https://{yourDomain}/oauth/token")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE

request = Net::HTTP::Post.new(url)
request.body = "grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fmfa-oob&mfa_token=%7BmfaToken%7D&oob_code=%7BoobCode%7D&binding_code=%7BuserEmailOtpCode%7D&client_id={yourClientId}&client_secret=%7ByourClientSecret%7D"

response = http.request(request)
puts response.read_body

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import Foundation

let postData = NSMutableData(data: "grant_type=http://auth0.com/oauth/grant-type/mfa-oob".data(using: String.Encoding.utf8)!)
postData.append("&mfa_token={mfaToken}".data(using: String.Encoding.utf8)!)
postData.append("&oob_code={oobCode}".data(using: String.Encoding.utf8)!)
postData.append("&binding_code={userEmailOtpCode}".data(using: String.Encoding.utf8)!)
postData.append("&client_id={yourClientId}".data(using: String.Encoding.utf8)!)
postData.append("&client_secret={yourClientSecret}".data(using: String.Encoding.utf8)!)

let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/oauth/token")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()

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If the call was successful, you'll receive a response in the following format, containing the access token:

{
  "id_token": "eyJ...i",
  "access_token": "eyJ...i",
  "expires_in": 600,
  "scope": "openid profile",
  "token_type": "Bearer"
}

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At this point, the authenticator is fully associated and ready to be used, and you have the authentication tokens for the user.

You can check at any point to verify whether an authenticator has been confirmed by calling the MFA Authenticators endpoint. If the authenticator is confirmed, the value returned for active is true.

Optionally, you can customize the emails that users receive. See Customize Email Templates for details.

Challenge with email

Get MFA token

Get an MFA token following the steps described in Authenticate With Resource Owner Password Grant and MFA.

Retrieve enrolled authenticators

To challenge the user, you need the authenticator_id for the factor you want to challenge. You can list all enrolled authenticators using the MFA Authenticators endpoint:

cURL
C#
Go
Java
Node.JS
Obj-C
...
- PHP
- Python
- Ruby
- Swift

curl --request GET \
  --url 'https://{yourDomain}/mfa/authenticators' \
  --header 'authorization: Bearer MFA_TOKEN' \
  --header 'content-type: application/json'

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var client = new RestClient("https://{yourDomain}/mfa/authenticators");
var request = new RestRequest(Method.GET);
request.AddHeader("authorization", "Bearer MFA_TOKEN");
request.AddHeader("content-type", "application/json");
IRestResponse response = client.Execute(request);

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package main

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

func main() {

	url := "https://{yourDomain}/mfa/authenticators"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("authorization", "Bearer MFA_TOKEN")
	req.Header.Add("content-type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := ioutil.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}

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HttpResponse<String> response = Unirest.get("https://{yourDomain}/mfa/authenticators")
  .header("authorization", "Bearer MFA_TOKEN")
  .header("content-type", "application/json")
  .asString();

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var axios = require("axios").default;

var options = {
  method: 'GET',
  url: 'https://{yourDomain}/mfa/authenticators',
  headers: {authorization: 'Bearer MFA_TOKEN', 'content-type': 'application/json'}
};

axios.request(options).then(function (response) {
  console.log(response.data);
}).catch(function (error) {
  console.error(error);
});

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#import <Foundation/Foundation.h>

NSDictionary *headers = @{ @"authorization": @"Bearer MFA_TOKEN",
                           @"content-type": @"application/json" };

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://{yourDomain}/mfa/authenticators"]
                                                       cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:10.0];
[request setHTTPMethod:@"GET"];
[request setAllHTTPHeaderFields:headers];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                if (error) {
                                                    NSLog(@"%@", error);
                                                } else {
                                                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                    NSLog(@"%@", httpResponse);
                                                }
                                            }];
[dataTask resume];

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$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{yourDomain}/mfa/authenticators",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "authorization: Bearer MFA_TOKEN",
    "content-type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

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import http.client

conn = http.client.HTTPSConnection("")

headers = {
    'authorization': "Bearer MFA_TOKEN",
    'content-type': "application/json"
    }

conn.request("GET", "/{yourDomain}/mfa/authenticators", headers=headers)

res = conn.getresponse()
data = res.read()

print(data.decode("utf-8"))

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require 'uri'
require 'net/http'
require 'openssl'

url = URI("https://{yourDomain}/mfa/authenticators")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE

request = Net::HTTP::Get.new(url)
request["authorization"] = 'Bearer MFA_TOKEN'
request["content-type"] = 'application/json'

response = http.request(request)
puts response.read_body

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import Foundation

let headers = [
  "authorization": "Bearer MFA_TOKEN",
  "content-type": "application/json"
]

let request = NSMutableURLRequest(url: NSURL(string: "https://{yourDomain}/mfa/authenticators")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()

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Challenge user with OTP

To trigger an email challenge, POST to the MFA Challenge endpoint using the corresponding authenticator_id and the mfa_token.

cURL
C#
Go
Java
Node.JS
Obj-C
...
- PHP
- Python
- Ruby
- Swift