Introduction to OAuth 1.0aver 0.3

Satoru Takeuchi <satoru.takeuchi@gmail.com>

Introduction● This document intends to be used for preparation for reading the

specification of OAuth 1.0a [1]○ OAuth 1.0a is *very complex* (at least for me) and hard to understand○ Although there is simpler OAuth2.0, OAuth1.0a still be used by many

web services● Omit some of features for simplicity

○ e.g. Out-of-bound authentication● Please let me know if you have any comments

Agenda● What is it● Advantages● Processing flow

What is it● The authorization way that a web service (Provider) permits third-party

services (Consumers) to use its functions on behalf of its users (Users)● Basic terms

Name Meaning Typical example

Provider An arbitrary web service Famous SNS services like Facebook and Twitter

Consumer A service requires Provider’s function to implement its function

Facebook clients and Twitter clients

User User of both Provider and Consumer You

Advantages● Can reduce security risks compare with password authentication

○ Don’t need to give Consumer unnecessary information and authorization

password authentication OAuth

The information which User gives Consumers

User ID and password The tokens only used for using the subset of Provider’s function

Authorized Provider’s functions

All functions The subset of Provider’s functions that Consumer requests and user permits

Processing flow● Describe the processing flow as the following order

a. Overview of all processesb. When each process is usedc. The summary of each process

■ Sequence diagram■ The explanation for each sequence

Processing flow: overviewUser Consumer Provider

1) Register itself as Consumer2) Authorize Consumer

3) Authenticate “Authorized” Consumer

4) Use Provider’s functions5) Rescind Customer’s Authorization

6) Unregister itself

When each process is usedUser Consumer Provider

1) Register itself as Consumer2) Authorize Consumer

3) Authenticate “Authorized” Consumer

4) Use Provider’s functions5) Rescind Customer’s Authorization

6) Unregister itself

Used once per starting service of a Consumer

Used once per stopping service of a Consumer

When each process is usedUser Consumer Provider

1) Register itself as Consumer2) Authorize Consumer

3) Authenticate “Authorized” Consumer

4) Use Provider’s functions5) Rescind Customer’s Authorization

6) Unregister itself

Used once per a User starts to use a Consumer

Used once per a User stops using a Consumer

When each process is usedUser Consumer Provider

1) Register itself as Consumer2) Authorize Consumer

3) Authenticate “Authorized” Consumer

4) Use Provider’s functions5) Rescind Customer’s Authorization

6) Unregister itself

Used once per a User starts to use a Consumer, or previous authentication timed out

When each process is usedUser Consumer Provider

1) Register itself as Consumer2) Authorize Consumer

3) Authenticate “Authorized” Consumer

4) Use Provider’s functions5) Rescind Customer’s Authorization

6) Unregister itself

Used once per a Consumer uses a Provider’s function

The summary of each process● Describe the following processes

a. Register a service as Consumerb. Authorize Consumerc. Authenticate “Authorized” Consumerd. Use Provider’s function

● Don’t describe other processesa. How these processes are done depend on each Provider very much

Register a service as ConsumerConsumer Provider

1) Visit Registration URI

2) List of functions exported to Consumers

3) Declare functions to use on behalf of Users

4) The information for authenticating Consumer

Register a service as Consumer1. Consumer: Visit Provider’s registration URI2. Consumer: Give the list of function exported to Consumers3. Consumer: Declare what kind of functions will it use, from the list of

functions which Provider offers4. Provider: Give Consumer the following tokens

○ consumer_key: Used for identifying Consumer○ consumer_secret: Used for authenticating Consumer

Prepare to authorize ConsumerConsumer Provider

1) Make and sign a request

2) Send the signed request

3) Authenticate Consumer4) Give the information needed by authorization request

Prepare to authorize Consumer1. Consumer: Make a request from the following information

○ consumer_key○ etc

2. Consumer: Sign the request with consumer_secret3. Consumer: Send the request to Provider’s request token URI

○ How to get this URI depends on each Provider4. Provider: Authenticate Consumer5. Provider: Give the following information to Consumer

○ request token: Used for identifying the authorizing request○ request token secret: Used for the authorizing request

Authorize ConsumerUser Consumer Provider

4) Give ID/password

1) Redirect to Provider’s authorization URI with callback URI

5) Ask for authorizing Consumer to use the list of functions

2) Redirected

3) Request ID/password

6) Answer “Yes”7) Redirect to callback URI with information for identifying “Authorized” Consumer

8) Redirected

Authorize Consumer1. Consumer: Make a request with the following information

○ request key○ Callback: URI to which should be redirected after authorization○ etc

2. Consumer: Sign the request with request token secret3. Consumer: Redirect User to Provider’s authorization URI

○ How to get this URI depends on each Provider4. Provider: Authenticate User, typically with ID and password5. Provider: Ask for User whether authorize Consumer to use a subset of

Provider’s functions on behalf of User6. Provider: Give Consumer the following token

○ oauth_verifier: Used for identifying authorized Consumer7. Provider: Redirect User to callback URI

Authenticate “Authorized” Consumer

Consumer Provider

1) Make and sign a request

2) Send the signed request

3) Authenticate Consumer4) Give the information needed by using Provider’s functions

Authenticate “authorized” Consumer1. Consumer: Make a request from the following information

○ consumer_key○ request token○ oauth_verifier○ etc

2. Consumer: Sign the request with the key constructed from consumer_secret and request token secret

3. Consumer: Send the request to Provider’s access Token URI○ How to get this URI depends on each Provider

4. Provider: Authenticate Consumer5. Provider: Give Consumer the following tokens

○ access token: Used for identifying authorized Consumer○ access token secret: Used for authenticating “authorized” Consumer

Use Provider’s functionsUser Consumer Provider

2) Make and sign a request

1) Use Consumer’s function

3) Send the signed request to Provider’s API URI

4) Authenticate Consumer

5) Execute a requested function

6) Return the result

7) Return the result

Use Provider’s functions1. User: Use Consumer’s function requires Provider’s function2. Consumer: Make a request from the following information

○ API’s parameters○ access token○ etc

3. Consumer: Sign the request with the key constructed from consumer_secret and access token secret

4. Consumer: Send the request to Provider’s API URI5. Provider: Authenticate Consumer6. Provider: Execute a requested function7. Provider: Give the result of the API call to Consumer8. Consumer: Achieve its function with the result

References● [1] OAuth Core 1.0 Revision A

○ http://oauth.net/core/1.0a● [2] Zero to Hero ~ The Linkedin OAuth Dance by Taylor Singletary

○ http://www.slideshare.net/episod/linkedin-oauth-zero-to-hero● [3] OAuth Ruby example

○ http://wiki.openstreetmap.org/wiki/OAuth_ruby_examples