OAuth is a protocol that allows clients limited access to protected resources on behalf of a resource owner through delegated authorization. It addresses issues with directly sharing user credentials by using tokens issued by an authorization server to represent temporary and limited authorization to access a resource on behalf of a resource owner. The key components in OAuth are the resource owner, client, authorization server, and protected resource. OAuth uses grant types like authorization code, implicit, client credentials, and resource owner password credentials to obtain access tokens from the authorization server to access protected resources.

1. Demystifying
OAuth 2

2. Nice to meet you
Software Engineer @Colpatria Scotiabank
Making things happen!
Loves reading, programming and teaching.
@yurynino
@yurynino
@yurynino
yury.nino.roa

3. Agenda
● Why OAuth?
● What is OAuth?
● How to OAuth works?
● OAuth Grant Types

4. What is the problem?
You have DIFFERENT
accounts for LinkedIn and
Google.
LinkedIn wants to add
your Google contacts to
your LinkedIn profile.

5. The bad old days: credential sharing

6. Think in this ….
Taken from Oauth 2.0 in
Action

7. It was bad because ...
● Same credentials at the client and
the protected resource are required.
● It exposed the user’s password to
the client application.
Taken from Oauth 2.0 in Action

8. What if we were able to have
this kind of limited credential,
issued separately for each
client and each user
combination, to be used at a
protected resource?

9. OAuth is a protocol
designed to do
exactly that:
Delegating.

10. Taken from Oauth 2.0 in
Action
What is the new with OAuth?

12. A client is a piece of
software that
attempts to access the
protected resource on
behalf of the resource
owner.
Taken from Oauth 2.0 in Action

13. An Access Token is an
artifact issued by the
authorization server to
a client that indicates
the rights that the client
has been delegated.
Taken from Oauth 2.0 in Action

14. A protected
resource is
available through an
HTTP server and it
requires an OAuth
token to be accessed.
Taken from Oauth 2.0 in Action

15. A resource owner
is the entity that has
the authority to
delegate access to the
client. It isn’t a piece
of software.
Taken from Oauth 2.0 in Action

16. An authorization
server is an HTTP
server that provides
mechanisms for
allowing resource
owners to authorize
clients, and issues
tokens to the clients.
Taken from Oauth 2.0 in Action

17. Tokens, scopes, and authorization grants
An access token, sometimes
known as just a token is an
artifact issued by the
authorization server to a
client that indicates the
rights that the client has been
delegated.
OAuth a token represents the
combination of the client’s
requested access, the resource
owner that authorized the
client, and the rights conferred
during that authorization.
A scope is a
representation of a set of rights at
a protected resource. They are a
mechanism for limiting the access
granted to a client.

18. Are you paying attention?
1. Which components are no software?
2. Which components should know the token
content?

19. OAuth Dancing

20. Step 1

21. Response
from the Client
Redirect
is a GET

22. Step 2

23. Step 3

24. Step 5

25. Step 4

28. Step 6

29. Step 7

30. What is the new with OAuth?

32. Are you paying attention?
1. How does Resource Owner authenticate
before Authorization Server grant the
access to the Resource?
2. How do you think a granted authorization
is removed?

33. RFC 5849 https://tools.ietf.org/html/rfc5849

34. RFC 6749 https://tools.ietf.org/html/rfc6749

35. OAuth 2.0 is a delegation
protocol, letting someone,
who controls a resource, allow
a software application to
access that resource on their
behalf.
Taken from Oauth 2.0 in Action

36. Real-life examples of OAuth 2.0 in action
● StackOverflow allowing you to log in
with your Google account.
● Posting a status update from your
phone using the Facebook app.
● LinkedIn suggesting contacts for you
to add by looking at your Google
contacts.

37. Fundamental to the power of OAuth 2.0 is
the notion of delegation. Although OAuth 2.0
is often called an authorization protocol (and
this is the name given to it in the RFC which
defines it), it is a delegation protocol.

38. How to get an access token … Grant Types

39. Authorization Code

40. Implicit Grant Type
Taken from Oauth 2.0 in
Action

41. Implicit Grant Type

42. Client credentials
Taken from Oauth 2.0 in
Action

43. Client credentials

44. Resource owner credentials
Taken from Oauth 2.0 in
Action

45. Resource owner credentials

46. Assertion grant types
Taken from Oauth 2.0 in
Action

47. Choosing the appropriate grant type

48. OAuth 2.0 the good, the
bad, and the ugly