The document is a presentation by Lorna Jane Mitchell that covers the concepts of OAuth 1 and OAuth 2, detailing the steps involved in implementing OAuth for consumer and provider applications. It explains the OAuth workflow, including the processes for obtaining request and access tokens, user authorization, and the necessary components for both consuming and providing OAuth. Additionally, it discusses the differences between OAuth 1 and 2, as well as tools and resources for developers working with OAuth.

1. Implementing OAuth

2. About Me
• Lorna Jane Mitchell
• PHP Consultant/Developer
• Occasional writer/speaker/trainer
• Twitter: @lornajane
• Website: http://lornajane.net
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3. About Me
• Lorna Jane Mitchell
• PHP Consultant/Developer
• Occasional writer/speaker/trainer
• Twitter: @lornajane
• Website: http://lornajane.net
• I am excited about OAuth :)
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4. About This Talk
• Covering OAuth1 and OAuth2
• OAuth1 needs more explanation
• OAuth v1.0a is current stable
• OAuth2 in use by Google, Facebook and others
• Ask questions at any time
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5. About OAuth
• Provider has User data
• User wants data to be available to 3rd party
• User tells Provider to grant access to Consumer
• Access may be limited
• User can revoke at any time
• Provider can distinguish between User and Consumer
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6. OAuth Terminology
Provider The app with the interesting data
Consumer The app that wants the data
User Who the data belongs to
Token Random string
Secret Another random string, linked to a token
Verifier Another random string
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7. OAuth HowTo

8. OAuth Dance
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9. Dance Steps
• Step 0: Register as a consumer
• Step 1: Get a request token
• Step 2: Send the user to authenticate
• Step 3: Swap their verification for an access token
• Step 4: Consume data
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10. Step 0: Register
• Akin to registering for an API key
• Introduce the Provider and Consumer
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11. Step 1: Get A Request Token
Consumer asks for a request token from the Provider’s request token
endpoint, specifying the callback URL
We give the token to the user and send them to log in
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12. Step 2: User Grants Access
We send the user to the Provider, with the request token, to log in
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13. Step 2: User Grants Access
We send the user to the Provider, with the request token, to log in
The Provider returns them to us, at the callback URL, with a verifier code
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14. Devices Where Callback Won’t Work
It is hard to forward a user from a browser back to an app
• Instead we use "oob" as the callback parameter
• Provider displays verifier on screen
• User types code into app manually
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15. Step 3: Get an Access Token
Consumer makes a request to Provider’s access token endpoint with:
• Consumer key
• Request token
• Verifier
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16. Step 3: Get an Access Token
Consumer makes a request to Provider’s access token endpoint with:
• Consumer key
• Request token
• Verifier
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17. OAuth Theory

18. Transmitting OAuth Parameters
We have three choices:
• As query parameters on the URL
• Use an Authorization Header
• Include the data as POST data
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19. OAuth Request Token Fields
Asking for a request token looks like this:
https://api.login.yahoo.com/oauth/v2/
get_request_token?oauth_nonce=ce2130523f788f313f76314ed3965ea6
&oauth_timestamp=1202956957
&oauth_consumer_key=123456891011121314151617181920
&oauth_signature_method=plaintext
&oauth_signature=abcdef
&oauth_version=1.0
&oauth_callback="http://yoursite.com/callback"
http://developer.yahoo.com/oauth/guide/oauth-requesttoken.html
We supplied the oauth_consumer_key and oauth_callback but what are these
other fields?
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20. OAuth Request Token Fields
• signature method: How the request is signed. Typically
plaintext or HMAC-SHA1
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21. OAuth Request Token Fields
• signature method: How the request is signed. Typically
plaintext or HMAC-SHA1
• nonce: Cryptographic term meaning "Number Used Once". We
think of a number, then throw it away
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22. OAuth Request Token Fields
• signature method: How the request is signed. Typically
plaintext or HMAC-SHA1
• nonce: Cryptographic term meaning "Number Used Once". We
think of a number, then throw it away
• timestamp: Number of seconds since the epoch
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23. OAuth Request Token Fields
• signature method: How the request is signed. Typically
plaintext or HMAC-SHA1
• nonce: Cryptographic term meaning "Number Used Once". We
think of a number, then throw it away
• timestamp: Number of seconds since the epoch
• version: 1.0 in this instance (more on OAuth2 later)
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24. OAuth Request Token Fields
• signature method: How the request is signed. Typically
plaintext or HMAC-SHA1
• nonce: Cryptographic term meaning "Number Used Once". We
think of a number, then throw it away
• timestamp: Number of seconds since the epoch
• version: 1.0 in this instance (more on OAuth2 later)
• signature:
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25. OAuth Request Token Fields
• signature method: How the request is signed. Typically
plaintext or HMAC-SHA1
• nonce: Cryptographic term meaning "Number Used Once". We
think of a number, then throw it away
• timestamp: Number of seconds since the epoch
• version: 1.0 in this instance (more on OAuth2 later)
• signature:
If you care, read this: http://bit.ly/gTJGPZ
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26. Practical Examples

27. OAuth Tools
PHP tools for OAuth:
• Pecl OAuth
• http://uk2.php.net/manual/en/class.oauth.php
• Talk examples use this
• Zend OAuth
• http://framework.zend.com/manual/en/zend.oauth.html
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28. Providing and Consuming OAuth
• Consuming:
• relatively easy
• used for authenticating against e.g. twitter
• Providing:
• more overhead than consuming
• great way to give access to applications
• needs multiple pages and endpoints as well as the API itself
Provider code with dark background
Consumer code with a blue background
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29. Provider: Auxiliary Web Pages
There are some additional functions to provide as a provider:
• Consumer signup page, like an API key
• User authorisation step to allow/deny access for this consumer
• Rights management page so users can control/revoke access later
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30. Provider: Step 0, Consumer Keys
This is straightforward
• Generate a key and a secret, store them
• Return them to the consumer to use
• Can use OAuth libraries, or not
$hash = sha1(mt_rand()); // there are many ways to do this
$consumer_key = substr($hash,0,30);
$consumer_secret = substr($hash,30,10);
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31. Provider: Handling OAuth Requests With Pecl
For every incoming request, for tokens and in normal operation, we’ll have
code like this:
$this->provider = new OAuthProvider();
// set names of functions to be called by the extension
$this->provider->consumerHandler(array($this,'lookupConsumer'));
$this->provider->timestampNonceHandler(
array($this,'timestampNonceChecker'));
$this->provider->tokenHandler(array($this,'tokenHandler'));
// no access token needed for this URL only
$this->provider->setRequestTokenPath('/v2/oauth/request_token');
$this->provider->checkOAuthRequest();
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32. Step 1
consumer key, callback
Consumer Provider
request token, request secret
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33. Consumer: Step 1, Request Token
$config = array();
$config['request_uri'] = 'http://api.local/v2/oauth/request_token';
$config['consumer_key'] = 'akey';
$config['consumer_secret'] = 'asecret';
$oauth = new OAuth($config['consumer_key'],
$config['consumer_secret']
);
$oauth->setAuthType(OAUTH_AUTH_TYPE_URI);
$req = $oauth->getRequestToken($config['request_uri'], "oob");
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34. Provider: Step 1, Request Token Request
• Check oauth signature and consumer key
• Generate a request token and store it
• Return the request token
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35. Provider: Step 1, Generate Request Token
Retrieve the callback, and make the token and secret:
// remember we're in URI mode
parse_str($_SERVER['QUERY_STRING'], &$parameters);
$callback = $parameters['oauth_callback'];
$request_token = bin2hex($provider->generateToken(4));
$request_token_secret = bin2hex($provider->generateToken(12));
We then simply echo the resulting variables in query format, e.g.
echo 'login_url = http://api.joindin.local/user/oauth_allow?' .
'request_token = ' . $request_token .
'&request_token_secret = ' . $request_token_secret .
'&oauth_callback_confirmed = true';
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36. Storing Request Tokens
Storage is simple, again, you know all this
+----------------------+--------------+
| Field | Type |
+----------------------+--------------+
| id | int(11) |
| consumer_key | varchar(30) |
| request_token | varchar(8) |
| request_token_secret | varchar(32) |
| callback | varchar(400) |
| verification | varchar(20) |
| authorised_user_id | int(11) |
| created_date | timestamp |
+----------------------+--------------+
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37. Step 2, User Grants Access
User grants access
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38. Provider: Step 2, Granting/Denying Access
User grants access:
• store user id against request token
• generate a verifier code and store that too
User denies access:
• delete request token
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39. Step 2, For Devices
Instead of forwarding the user, give them a code to use
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40. Step 3
consumer key,
request token, verifier
Consumer Provider
access token
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41. Consumer: Step 3, Request an Access Token
$oauth = new OAuth($config['consumer_key'],
$config['consumer_secret']);
// request token, request token secret and verification all set
// by earlier steps, and loaded into $config
try{
$oauth->setToken(
$config['request_token'],
$config['request_token_secret']);
$access = $oauth->getAccessToken($config['access_uri'], null,
$config['verification']);
} catch (OAuthException $e) {
echo $e->getMessage();
}
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42. Provider: Step 3, Generate Access Token
Generate and store access token and secret, then return:
echo "oauth_token=" . $tokens['oauth_token']
. '&oauth_token_secret=' . $tokens['oauth_token_secret'];
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43. Storing Access Tokens
+---------------------+-------------+
| Field | Type |
+---------------------+-------------+
| id | int(11) |
| consumer_key | varchar(30) |
| access_token | varchar(16) |
| access_token_secret | varchar(32) |
| user_id | int(11) |
| created_date | timestamp |
| last_used_date | datetime |
+---------------------+-------------+
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44. Step 4
consumer key,
access token, API request
Consumer Provider
API response
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45. Consumer: Step 4, Subsequent Requests
$oauth = new OAuth($config['consumer_key'],
$config['consumer_secret']);
// from the getAccessToken call
$oauth->setToken($oauth_token, $oauth_token_secret);
$result = $oauth->fetch("http://api.local/usual/call/here");
if($result) {
$response = $oauth->getLastResponse();
}
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46. Debugging
• For pecl_oauth:
• Use OAuth::enableDebug() to turn on verbose debugging
• The debug information is available in OAuth::debugInfo
• For the provider, use OAuthProvider::reportProblem()
• Wireshark or Charles Proxy
• http://www.wireshark.org/
• http://www.charlesproxy.com/
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47. Other OAuth Types

48. 3-legged OAuth
So far we have discussed 3-legged OAuth
• Three parties are involved
• Consumer
• Provider
• User
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49. 2-legged OAuth
2-legged OAuth is also an option
• Only two parties involved now
• Provider
• User/Client
• Step 0: User signs up for credentials similar to consumer key/secret
• Step 4: User makes request using
• their key and secret
• empty token details
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50. OAuth 2
• Same principles and intention
• Spec still at draft stage officially
• Used by Google, Facebook and others
• Aims to be less complicated than OAuth 1
• Intended to be more scalable - provider split into resources and auth
servers
• No signing, SSL recommended instead
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51. OAuth2 Outline
+--------+ +---------------+
| |--(A)- Authorization Request ->| Resource |
| | | Owner |
| |<-(B)-- Authorization Grant ---| |
| | +---------------+
| |
| | Authorization Grant & +---------------+
| |--(C)--- Client Credentials -->| Authorization |
| Client | | Server |
| |<-(D)----- Access Token -------| |
| | +---------------+
| |
| | +---------------+
| |--(E)----- Access Token ------>| Resource |
| | | Server |
| |<-(F)--- Protected Resource ---| |
+--------+ +---------------+
Diagram from OAuth2 spec
http://tools.ietf.org/html/draft-ietf-oauth-v2-15
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52. Authorization Grant
Can take many forms
• Username and password
• used once to obtain an access token
• or just used as access token
• Client credentials
• client has prearranged access to the resource
• Implicit
• an access token provided some other way
• Authorization Code
• similar to OAuth 1, send user to talk to Auth Server and get
verification codes
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53. Access Tokens and Refresh Tokens
Refresh Tokens are an optional addition to OAuth 2
• Auth Server can return a refresh token with an access token
• Refresh token has longer validity
• Can be exchanged for an access token when combined with other
details
• Compare with re-entering your password at intervals
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54. The State of OAuth
• OAuth 1
• already in use
• a faff!
• OAuth 2
• still being finalised
• different approach to same problem
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55. Questions?

56. Resources
• PHP Manual: http://uk2.php.net/manual/en/book.oauth.php
• Rasmus’ OAuth Provider Example: http://bit.ly/i76Tzx
• Yahoo Developer Network Documentation:
http://developer.yahoo.com/oauth/guide/
• Eran Hammer-Lahav’s blog: http://hueniverse.com
• 2-legged OAuth post: http://bit.ly/ejQRoK
• OAuth 2 Draft Spec:
http://tools.ietf.org/html/draft-ietf-oauth-v2-15
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57. Thanks!
Thanks!
http://joind.in/3243/
@lornajane
http://lornajane.net/
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