Duo Auth API v1 (Legacy)

Overview

Authentication Process

When a user (bob) wishes to authenticate, your application usually would proceed roughly as follows:

1. Authenticate bob via primary factor (e.g. password)
2. Perform a preauth request to Duo to get a list of factors available for bob and ensure they are currently permitted to authenticate.
3. Display a list of factors to bob and allow them to select one
4. Perform an auth request to Duo with bob's chosen factor

Normally, the auth method will not return a response until the authentication process has completed. However, it permits an optional parameter, async. If the application provides a value of '1' for the async argument, then the auth method will instead return a unique identifier which can be used to poll the status of the authentication attempt.

Review the API Details to see how to construct your first API request.

Documented properties will not be removed within a stable version of the API. Once a given API endpoint is documented to return a given property, a property with that name will always appear (although certain properties may only appear under certain conditions, like if the customer is using a specific edition).

Properties that enumerate choices may gain new values at any time, e.g. the device platform value could return new device platforms that did not previously exist. Duo will update our API documentation with new values in a timely fashion.

New, undocumented properties may also appear at any time. For instance, Duo may make available a beta feature involving extra information returned by an API endpoint. Until the property is documented here its format may change or it may even be entirely removed from our API.

First Steps

Before starting:

1. Sign up for a Duo account.

2. Log in to the Duo Admin Panel and navigate to Applications → Protect an Application.

3. Locate the entry for Auth API in the applications list. Click Protect to the far-right to configure the application and get your integration key, secret key, and API hostname. You'll need this information to complete your setup. See Protecting Applications for more information about protecting applications with Duo and additional application options.

   Treat your secret key like a password

   The security of your Duo application is tied to the security of your secret key (skey). Secure it as you would any sensitive credential. Don't share it with unauthorized individuals or email it to anyone under any circumstances!

API Methods

/ping

The /ping method acts as a "liveness check" that can be called to verify that Duo is up before trying to call other methods. Unlike the other API methods, this one does not have to be signed with the Authorization header and may be sent over HTTP for speed.

GET /rest/v1/ping

A successful response will be returned in the standard container format described above and will contain pong in the response field.

Example successful response (JSON):

{
  "stat": "OK",
  "response": "pong"
}

/check

The /check method can be called to verify that the integration and secret keys are valid, and that the signature is being generated properly.

GET /rest/v1/check

A successful response will be returned in the standard container format described above and will contain valid in the response field.

Available parameters:

None.

Response codes:

Example successful response (JSON):

{
  "stat": "OK",
  "response": "valid"
}

/logo

The /logo endpoint provides a programmatic way to retrieve your stored logo.

GET /rest/v1/logo

Parameters

None required.

Response Codes

Response Format

On success, the response body is Content-Type image/png, containing the logo.

On failure, the response is the standard error JSON.

/preauth

The /preauth method determines whether a user is authorized to log in, and (if so) returns the user's available authentication factors.

POST /rest/v1/preauth

Available parameters:

The response will be returned in the container format described above. For successful responses, the payload will contain the following key/value pairs:

Example successful response:

{
  "stat": "OK",
  "response": {
      "result": "auth",
      "factors": {
          "default": "push1",
          "1": "push1",
          "2": "push2",
          "3": "phone1",
          "4": "phone2",
          "5": "sms1",
          "6": "sms2"
      },
      "prompt": "Duo login for bob\n\n 1. Duo Push to XXX-XXX-1234\n 2. Duo Push to XXX-XXX-5678\n 3. Phone call to XXX-XXX-1234\n 4. Phone call to XXX-XXX-5678\n 5. SMS passcodes to XXX-XXX-1234 (next code starts with: B)\n 6. SMS passcodes to XXX-XXX-5678\n\nPasscode or option (1-6): "
  }
}

/auth

The /auth method performs second-factor authentication for a user by verifying a passcode, placing a phone call, or sending a push notification to the user's smartphone app.

POST /rest/v1/auth

Parameters:

Additionally, you will need to pass some factor-specific parameters:

The response will be returned in the container format described above. For successful responses, the payload will contain the following key/value pairs:

If "async" was not enabled:

Example successful response (JSON):

{
  "stat": "OK",
  "response": {
    "status": "Success. Logging you in...",
    "result": "allow"
  }
}

Example failure response due to factor restriction as a result of Risk-based Factor Selection policy:

{
  "stat": "OK",
  "response": {
        "result": "deny",
        "status": "Selected number is restricted from Duo Push authentication"
  },
}

If "async" was enabled:

Example successful response (JSON):

{
  "stat": "OK",
  "response": {
    "txid": "45f7c92b-f45f-4862-8545-e0f58e78075a"
  }
}

/status

The /status method "long-polls" for the next status update from the authentication process for a given transaction. That is to say, if no status update is available at the time the request is sent, it will wait until there is an update before returning a response.

GET /rest/v1/status

Available parameters:

The response will be returned in the container format described above. For successful responses, the payload will contain the following key/value pairs:

Example successful response (JSON):

{
  "stat": "OK",
  "response": {
    "status": "Success. Logging you in...",
    "result": "allow"
  }
}

API Details

Base URL

All API methods use your API hostname, https://api-XXXXXXXX.duosecurity.com. Obtain this value from the Duo Admin Panel and use it exactly as shown there.

Methods always use HTTPS. Unsecured HTTP is not supported.

Request Format

All requests must have "Authorization" and "Date" headers.

If the request method is GET or DELETE, URL-encode parameters and send them in the URL query string like this: ?realname=First%20Last&username=root. They still go on a separate line when creating the string to sign for an Authorization header.

Send parameters for POST requests in the body as URL-encoded key-value pairs (the same request format used by browsers to submit form data). The header "Content-Type: application/x-www-form-urlencoded" must also be present.

When URL-encoding, all bytes except ASCII letters, digits, underscore ("_"), period ("."), tilde ("~"), and hyphen ("-") are replaced by a percent sign ("%") followed by two hexadecimal digits containing the value of the byte. For example, a space is replaced with "%20" and an at-sign ("@") becomes "%40". Use only upper-case A through F for hexadecimal digits.

A request with parameters, as a complete URL, would look something like this: https://api-XXXXXXXX.duosecurity.com/admin/v1/users?realname=First%20Last&username=root (substituting the actual API method path and parameters used in your request).

Response Format

Responses are formatted as a JSON object with a top-level stat key.

Successful responses will have a stat value of "OK" and a response key. The response will either be a single object or a sequence of other JSON types, depending on which endpoint is called.

{
  "stat": "OK",
  "response": {
    "key": "value"
  }
}

Values are returned as strings unless otherwise documented.

Unsuccessful responses will have a stat value of "FAIL", an integer code, and a message key that further describes the failure. A message_detail key may be present if additional information is available (like the specific parameter that caused the error).

{
  "stat": "FAIL",
  "code": 40002,
  "message": "Invalid request parameters",
  "message_detail": "username"
}

The HTTP response code will be the first three digits of the more specific code found inside the JSON object. Each endpoint's documentation lists HTTP response codes it can return. Additionally, all API endpoints that require a signed request can return the following HTTP response codes:

Authentication

The API uses HTTP Basic Authentication to authenticate requests. Use your Duo application's integration key as the HTTP Username.

Generate the HTTP Password as an HMAC signature of the request. This will be different for each request and must be re-generated each time.

To construct the signature, first build an ASCII string from your request, using the following components:

Then concatenate these components with (line feed) newlines. For example:

Tue, 21 Aug 2012 17:29:18 -0000
POST
api-xxxxxxxx.duosecurity.com
/rest/v1/auth
auto=auto&factor=auto&hostname=wks01&ipaddr=10.2.3.4&user=narroway

GET requests also use this five-line format (note the blank line as this request has no parameters):

Tue, 21 Aug 2012 17:29:18 -0000
GET
api-xxxxxxxx.duosecurity.com
/rest/v1/check
 

Lastly, compute the HMAC-SHA1 of this canonical representation, using your Duo application's secret key as the HMAC key. Send this signature as hexadecimal ASCII (i.e. not raw binary data). Use HTTP Basic Authentication for the request, using your integration key as the username and the HMAC-SHA1 signature as the password.

For example, here are the headers for the above POST request to api-XXXXXXXX.duosecurity.com/rest/v1/auth, using DIWJ8X6AEYOR5OMC6TQ1 as the integration key and Zh5eGmUq9zpfQnyUIu5OL9iWoMMv5ZNmk3zLJ4Ep as the secret key:

Date: Tue, 21 Aug 2012 17:29:18 -0000
Authorization: Basic RElXSjhYNkFFWU9SNU9NQzZUUTE6MzM5MTZlMTJhYjI4MjZkNTRmMDcyNjY5ODc3ZmRjYTIxMTJlNTE1ZA==
Host: api-XXXXXXXX.duosecurity.com
Content-Length: 92
Content-Type: application/x-www-form-urlencoded

Separate HTTP request header lines with CRLF newlines.

The following Python function can be used to construct the "Authorization" and "Date" headers:

import base64, email.utils, hmac, hashlib, urllib
  ​ ​
def sign(method, host, path, params, skey, ikey):
    """
    Return HTTP Basic Authentication ("Authorization" and "Date") headers.
    method, host, path: strings from request
    params: dict of request parameters
    skey: secret key
    ikey: integration key
    """
  ​
    # create canonical string
    now = email.utils.formatdate()
    canon = [now, method.upper(), host.lower(), path]
    args = []
    for key in sorted(params.keys()):
        val = params[key].encode("utf-8")
        args.append(
            '%s=%s' % (urllib.parse.
                       quote(key, '~'), urllib.parse.quote(val, '~')))
    canon.append('&'.join(args))
    canon = '\n'.join(canon)
  ​
    # sign canonical string
    sig = hmac.new(bytes(skey, encoding='utf-8'),
                   bytes(canon, encoding='utf-8'),
                   hashlib.sha1)
    auth = '%s:%s' % (ikey, sig.hexdigest())
  ​
    # return headers
    return {'Date': now, 'Authorization': 'Basic %s' % base64.b64encode(bytes(auth, encoding="utf-8")).decode()}

import base64, email, hmac, hashlib, urllib

def sign(method, host, path, params, skey, ikey):
    """
    Return HTTP Basic Authentication ("Authorization" and "Date") headers.
    method, host, path: strings from request
    params: dict of request parameters
    skey: secret key
    ikey: integration key
    """

    # create canonical string
    now = email.Utils.formatdate()
    canon = [now, method.upper(), host.lower(), path]
    args = []
    for key in sorted(params.keys()):
        val = params[key]
        if isinstance(val, unicode):
            val = val.encode("utf-8")
        args.append(
            '%s=%s' % (urllib.quote(key, '~'), urllib.quote(val, '~')))
    canon.append('&'.join(args))
    canon = '\n'.join(canon)

    # sign canonical string
    sig = hmac.new(skey, canon, hashlib.sha1)
    auth = '%s:%s' % (ikey, sig.hexdigest())

    # return headers
    return {'Date': now, 'Authorization': 'Basic %s' % base64.b64encode(auth)}

Troubleshooting

Need some help? Take a look at our Auth API Knowledge Base articles or Community discussions. For further assistance, contact Support.