1. Authentication
Cookies vs JWTs and why you’re doing it wrong

2. The power of an agency at your fingertips

3. WelcometoUtahJS

4. HowYou’reDoingItNow
Cookies are so
20th century

5. CookieAuthentication Cookie Auth
• Stores a Session ID
• Looks up the user in a database
• All session information stored server side
Concerns
• What do you do as your application scales?
• How do you route each request back to the same server
that stored the session?
• As your app grows virally, how do you keep costs down?

6. What’saJWT?
What’s a JWT?
JWT (pronounced jot) is
a JSON Web Token

7. ThreePartsofaJWT • Header
• Declares that it is a JWT
• Specifies the decoding algorithm
• Claims
• Plain text data (encoded with base64)
• Typically json object
• Signature
• Header + Claims encrypted using a server side secret key
• Only matches if header and claims aren’t tampered with

8. SampleJWT Header
Second Part / Payload
Third Part / Signature
Result

9. ServertoClient Successful Login Generate JWT Send to Client

10. ClientReceivesToken Check Token Read Claims Base64 Decode

11. ServerVerifiesJWT Check Token Decode Token Validate Time

12. Implementation • Generated on login and stored in the browser
• JWT is submitted with requests as an Authorization header
or in a query string
Authorization: Bearer {{full JWT}}
• Verification happens by regenerating the signature from
the original plaintext
• After verification, check expiration timestamps
• Continue on your merry way 

13. WhyshouldIcare?

14. AuthTransmission
Always tagging along

15. AuthTransmission
• Typically very small
(4k hard limit)
• Sent with every request to
domain – overhead
• Authorizing static files
included
• Cookie specific storage
• Can get larger depending
on info stored in token
(8k soft limit)
• Only sent when necessary
• Uses signed requests,
more cumbersome
• Stored in LocalStorage or
SessionStorage
Cookies JWT

16. Cross-domain/CORS

17. Cross-domain/CORS
• Very difficult across
domains
• Can be accessed from
multiple subdomains
• Pre-flight request if using
application/json
• Works from any domain
• Local storage only
accessible from storing
subdomain
• Pre-flight request
Cookies JWT

18. Security

19. Security
• Subject to CSRF attacks
• HttpOnly makes XSS hard
• Secure flag forces SSL --
Man in the Middle (MITM)
• Taking cookie with browser
access is easy
• Not subject to CSRF
• No XSS protection
• SSL managed in-app
• LocalStorage is no
different
Cookies JWT

20. Compatibility

21. Compatibility
• Less support for mobile
• Must be set by server
• Can’t use for external API
requests
• Standard for mobile auth
• Can be generated by
anyone with secret key
• Easy to use for public API
Cookies JWT

22. Stateless
Apparently they’re a band

23. Stateless
• Contains a session id
• Requires a database
lookup on every request
• Server-side sessions
require subsequent
requests to hit same server
• Scaling difficult
• Contains verified user
information
• No db lookups required
• State is stored on client
• Scales easily
Cookies JWT

24. You’recrazy!

25. ThingstoRemember • Base64 is NOT secure, encrypt sensitive info
• Don’t write your own server-side implementation
• There are some good SaaS companies that make this
easier on you:
• Auth0*
• UserApp
• Firebase
• Keep your secret key SECRET
Provided inspiration for this presentation: https://auth0.com/blog/2014/01/07/angularjs-authentication-with-cookies-vs-token/
*

26. FurtherInvestigation • Angular httpAuthInterceptor
• Silently add userAgent to JWT
• Token heartbeat (refresh on each request)
• Two level authentication (GitHub style)

27. DerekPerkins
@Derek_Perkins
linkedin.com/in/derekperkins
github.com/derekperkins
derek@derekperkins.com