Authentication with JSON Web Tokens 2016. 06. 04 pyconTW Shuhsi Lin Data Engineer of Throughtek 

JSON Web Tokens 2 JWT 

“jot” 3 

1. Why we need authorization 2. The idea of Authorization Server 3. How to implement JWT - PyJWT - Django & Flask 4 Agenda 

About Me Data Engineer of Throughtek Currently working with - IoT -PaaS - Streaming processing framework - WebAPI - Lurking in PyHug, Taipei.py and various Meetups 5 Shuhsi Lin [email protected] [email protected] 

I A A Identity “Who are you?” 6 Authentication “OK, how can you prove it?” Authorization “What can you do?” Identity and Access Management (IAM) 

Copyright © 2016 ThroughTek Co., Ltd. All rights reserved. Confidential. Do not distribute. 7 • Generic applications • Customization service • Kalay Kit • FW integration micro-service system 

Turnkey Solution for Rapid IoT Deployment Kalay Platform 

What is Kalay? 9 

Copyright © 2016 ThroughTek Co., Ltd. All rights reserved. Confidential. Do not distribute. 10 10 “Handshake” in the language of the aboriginal Tao people of Taiwan Connecting All Devices 

Copyright © 2016 ThroughTek Co., Ltd. All rights reserved. Confidential. Do not distribute. 11 User Account • Define multiple user types • Manage and control user permission • Monitor login status and activity UID & Device • Real time log analysis • Track connection status, IP, region • Monitor and backup log data Why we need Identity Management (Device and User Account) 

A server has to know who is requesting the resource 12 

How has authentication been done in web? 13 ● Server based ● Token based 

Server based authentication 14 user id/password 

Problems from Server based authentication ● Sessions ● Scalability ● Cross-Origin Resource Sharing (CORS) ● Cross-Site Request Forgery (CSRF) 15 

Token based authentication 16 user id/password Stateless 

Token based authentication ● Stateless and scalable servers ● Mobile application ready ● Pass authentication to other applications ● Extra security 17 

18 https://jwt.io/ 2,506 6,120 https://github.com/search?q=jwt http://stackoverflow.com/search?q=jwt ● Compact and Self-contained ● Across different programming languages ● Passed around easily 

JWT looks like? 19 Three strings separated by “.” aaaaaaaaa.bbbbbbbbb.ccccccccccc header payload signature 

20 https://jwt.io/#debugger-io don’t put sensitive data here 

How usually JSON Web Tokens work ? 21 

How usually JSON Web Tokens work ? 22 POST login/ user id/password https://auth0.com/learn/json-web-tokens/ return JWT token request with Header Authorization: Bearer create JWT Check JWT send responses 

What do we put in payload ● Reserved : predefined claim ● iss (issuer), exp (expiration time), sub (subject), aud (audience) ● and etc. ● Public: ● name, email, email_verified, and etc. ● http://www.iana.org/assignments/jwt/jwt.xhtml ● Private : custom claims 23 

How to implement it in python ? 24 

25 In [1]: import json In [2]: import hmac In [3]: from hashlib import sha256 In [4]: from base64 import urlsafe_b64encode In [5]: segments =[] In [6]: header_dict = { ...: 'typ': 'JWT', ...: 'alg': 'HS256' ...: } In [7]: json_header = json.dumps(header_dict).encode('utf-8') In [8]: header = urlsafe_b64encode(json_header) In [9]: segments.append(header) In [10]: segments Out[10]: [b'eyJ0eXAiOiAiSldUIiwgImFsZyI6ICJIUzI1NiJ9'] 

26 In [11]: payload_dict = { ....: 'user_id':'pythontw2016' ....: } In [12]: json_payload =json.dumps(payload_dict).encode('utf-8') In [13]: payload = urlsafe_b64encode(json_payload) In [14]: segments.append(payload) In [15]: segments Out[15]: [b'eyJ0eXAiOiAiSldUIiwgImFsZyI6ICJIUzI1NiJ9', b'eyJ1c2VyX2lkIjogInB5dGhvbnR3MjAxNiJ9'] 

27 In [16]: SECRET = b'secret' In [17]: signing_input = b'.'.join(segments) In [18]: sig = hmac.new (SECRET, signing_input, sha256) In [19]: signature = urlsafe_b64encode(sig.digest()) In [20]: segments.append(signature) In [21]: segments Out[21]: [b'eyJ0eXAiOiAiSldUIiwgImFsZyI6ICJIUzI1NiJ9', b'eyJ1c2VyX2lkIjogInB5dGhvbnR3MjAxNiJ9', b'qhevGfl16LBHjRG2wb6xDitbGt3lDK-2iUYCsLseCJY='] In [22]: token = b'.'.join(segments) In [23]: token Out[23]: b'eyJ0eXAiOiAiSldUIiwgImFsZyI6ICJIUzI1NiJ9.eyJ1c2VyX2lkIjogInB5dGhvbnR3MjAx NiJ9.qhevGfl16LBHjRG2wb6xDitbGt3lDK-2iUYCsLseCJY=' Test this token in https://jwt.io/ 

We don’t need to reinvent the wheel 28 

29 https://jwt.io/#libraries-io PyJWT 

30 PyJWT Django DRF JWT Auth json hmac base64 hashlib Flask-JWT 

PyJWT >>> import jwt >>> jwt_token = jwt.encode({ 'payload': ‘pycontw 2106’ }, 'secret', algorithm='HS256') 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJwYXlsb2FkIjoicHljb250dyAyMDE2In 0.TRRENrqd8lc3_AQeo3IRheVkZpMkcqXqYQi891pFL6w’ >>> jwt.decode(jwt_token, 'secret', algorithms=[ 'HS256']) {'payload': 'pycontw 2016'} 31 https://github.com/jpadilla/pyjwt pip install PyJWT see more in Registered Claim Names 

Example Scenarios 32 

Copyright © 2016 ThroughTek Co., Ltd. All rights reserved. Confidential. Do not distribute. 33 • Generic applications • Customization service • Kalay Kit • FW integration micro-service system 

Kalay services Users Kalay AM Kalay DM JWT login Kalay DC mqtt/https shared keys shared keys shared keys Kalay Cloud Kalay services Kalay services devices actions (bind/view/control….) with JWT 

Messaging API for Mobile Apps and Websites ● http://api.diuit.com/ 

Authentication with JWT for security purpose 1. User sends login request with credential 2. Auth user on your server (account server) 3. Request for Nonce on Diuit server 4. Obtain nonce from Diuit server 5. Use JWT to request session token 6. Obtain session token from Diuit server 7. Send session token back to messaging client 8. Authenticate messaging client on Diuit server using "loginWithAuthToken" JWT Your own account server user login nonce =>create JWT { "typ": "JWT", "alg": "RS256" "cty": "diuit-eit;v=1" "kid": ${EncryptionKeyId} } header { "iss": ${DIUIT_APP_ID} "sub": ${UNIQUE_USER_ID} "iat": ${CURRENT_TIME_IN_ISO8601_FORMAT} "exp":${SESSION_EXPIRATION_TIME_IN_ISO8601_FORMAT} "nce": ${AUTHENTICATION_NONCE} } payload 

Django REST framework JWT JSON Web Token Authentication support for Django REST Framework 37 

Django DRF JWT 38 https://github.com/GetBlimp/django-rest-framework-jwt Steps: ● pip install djangorestframework-jwt ● add JSONWebTokenAuthentication in Django REST framework's DEFAULT_AUTHENTICATION_CLASSES (settings.py) ● add URL routes (urls.py) ○ provide JWT token (obtain_jwt_token) ○ refresh token (refresh_jwt_token) ○ verify token (verify_jwt_token) ● additional settings Requirements ● Python (2.7, 3.3, 3.4) ● Django (1.8, 1.9) ● Django REST Framework (3.0, 3.1, 3.2, 3.3) 

settings.py 39 REST_FRAMEWORK = { 'DEFAULT_PERMISSION_CLASSES': ( 'rest_framework.permissions.IsAuthenticated', ), 'DEFAULT_AUTHENTICATION_CLASSES': ( 'rest_framework.authentication.SessionAuthentication', 'rest_framework.authentication.BasicAuthentication', 'rest_framework_jwt.authentication.JSONWebTokenAuthentication', ), } from rest_framework_jwt.views import obtain_jwt_token #... urlpatterns = patterns( '', # ... url(r'^api-token-auth/', obtain_jwt_token), url(r'^api-token-refresh/', refresh_jwt_token), url(r'^api-token-verify/', verify_jwt_token), ) urls.py http://getblimp.github.io/django-rest-framework-jwt/ 

Flask-JWT Add basic JWT features to your Flask application 40 https://pythonhosted.org/Flask-JWT/ 

Flask-JWT from flask import Flask from flask_jwt import JWT, jwt_required, current_identity from werkzeug.security import safe_str_cmp 41 https://pythonhosted.org/Flask-JWT/ pip install Flask-JWT class User(object): def __init__(self, id, username, password): self.id = id self.username = username self.password = password def __str__(self): return "User(id='%s')" % self.id users = [ User(1, 'user1', 'abcxyz'), User(2, 'user2', 'abcxyz'), ] username_table = {u.username: u for u in users} userid_table = {u.id: u for u in users} Minimum viable application configuration: 

42 app = Flask(__name__) app.debug = True app.config['SECRET_KEY'] = ' super-secret' jwt = JWT(app, authenticate, identity ) def identity(payload): user_id = payload['identity'] return userid_table.get(user_id, None) def authenticate(username, password): user = username_table.get(username, None) if user and safe_str_cmp(user.password.encode('utf-8'), password.encode('utf-8')): return user @app.route('/protected') @jwt_required() def protected(): return '%s' % current_identity if __name__ == '__main__': app.run() Configuration JWT_AUTH_URL_RULE: The authentication endpoint URL. Defaults to /auth https://pythonhosted.org/Flask-JWT/ jwt working 

Recap ● JWT (‘jot’) : header, payload, signature ● Stateless token-based authentication ● Use libraries ● PyJWT, Django DRF JWT , Flask-JWT ● Provide, refresh, verify JWT 43 

About JWT Ref: ● JWT ● https://jwt.io/ ● https://auth0.com/learn/json-web-tokens/ ● https://self-issued.info/docs/draft-ietf-oauth-json-web-token.html ● PyJWT (https://pyjwt.readthedocs.org/) ● django-rest-framework-jwt (http://getblimp.github.io/django-rest-framework-jwt/) ● Flask-JWT (https://pythonhosted.org/Flask-JWT/) ● DjangoCon US 2014 talk on JWT https://speakerdeck.com/jpadilla/djangocon-json-web-tokens ● JWT in Auth0 https://auth0.com/blog/2014/12/02/using-json-web-tokens-as-api-keys/ About Authentication ● https://www.owasp.org/index.php/Authentication_Cheat_Sheet and others: ● Kalay platform (http://www.throughtek.com.tw/kalay_overview.html) ● diuit messaging api (http://api.diuit.com/ , https://github.com/diuitAPI) ● icons: (https://thenounproject.com/) 44 

Thank you! Questions? 45