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Implementing OAuth with PHP

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Shows how to be an oauth consumer and provider from PHP - OAuth 1 - including handling of tokens, secrets, and handling the workflow for devices. Also covers the workflow for OAuth 2

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Implementing OAuth with PHP

  1. 1. Implementing OAuth
  2. 2. About Me • Lorna Jane Mitchell • PHP Consultant/Developer • Occasional writer/speaker/trainer • Twitter: @lornajane • Website: http://lornajane.net 2
  3. 3. About Me • Lorna Jane Mitchell • PHP Consultant/Developer • Occasional writer/speaker/trainer • Twitter: @lornajane • Website: http://lornajane.net • I am excited about OAuth :) 2
  4. 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 3
  5. 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 4
  6. 6. OAuth TerminologyProvider The app with the interesting dataConsumer The app that wants the dataUser Who the data belongs toToken Random stringSecret Another random string, linked to a tokenVerifier Another random string 5
  7. 7. OAuth HowTo
  8. 8. OAuth Dance 7
  9. 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 8
  10. 10. Step 0: Register • Akin to registering for an API key • Introduce the Provider and Consumer 9
  11. 11. Step 1: Get A Request TokenConsumer asks for a request token from the Provider’s request tokenendpoint, specifying the callback URLWe give the token to the user and send them to log in 10
  12. 12. Step 2: User Grants AccessWe send the user to the Provider, with the request token, to log in 11
  13. 13. Step 2: User Grants AccessWe 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 11
  14. 14. Devices Where Callback Won’t WorkIt 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 12
  15. 15. Step 3: Get an Access TokenConsumer makes a request to Provider’s access token endpoint with: • Consumer key • Request token • Verifier 13
  16. 16. Step 3: Get an Access TokenConsumer makes a request to Provider’s access token endpoint with: • Consumer key • Request token • Verifier 13
  17. 17. OAuth Theory
  18. 18. Transmitting OAuth ParametersWe have three choices: • As query parameters on the URL • Use an Authorization Header • Include the data as POST data 15
  19. 19. OAuth Request Token FieldsAsking 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.htmlWe supplied the oauth_consumer_key and oauth_callback but what are theseother fields? 16
  20. 20. OAuth Request Token Fields • signature method: How the request is signed. Typically plaintext or HMAC-SHA1 17
  21. 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 17
  22. 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 17
  23. 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) 17
  24. 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: 17
  25. 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 17
  26. 26. Practical Examples
  27. 27. OAuth ToolsPHP 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 19
  28. 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 itselfProvider code with dark backgroundConsumer code with a blue background 20
  29. 29. Provider: Auxiliary Web PagesThere 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 21
  30. 30. Provider: Step 0, Consumer KeysThis 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($hash,30,10); 22
  31. 31. Provider: Handling OAuth Requests With PeclFor every incoming request, for tokens and in normal operation, we’ll havecode like this:$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(); 23
  32. 32. Step 1 consumer key, callback Consumer Provider request token, request secret 24
  33. 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"); 25
  34. 34. Provider: Step 1, Request Token Request • Check oauth signature and consumer key • Generate a request token and store it • Return the request token 26
  35. 35. Provider: Step 1, Generate Request TokenRetrieve the callback, and make the token and secret:// remember were in URI modeparse_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 = . $request_token_secret . &oauth_callback_confirmed = true; 27
  36. 36. Storing Request TokensStorage is simple, again, you know all this+----------------------+--------------+| Field | Type |+----------------------+--------------+| id | int(11) || consumer_key | varchar(30) || request_token | varchar(8) || request_token_secret | varchar(32) || callback | varchar(400) || verification | varchar(20) || authorised_user_id | int(11) || created_date | timestamp |+----------------------+--------------+ 28
  37. 37. Step 2, User Grants AccessUser grants access 29
  38. 38. Provider: Step 2, Granting/Denying AccessUser grants access: • store user id against request token • generate a verifier code and store that tooUser denies access: • delete request token 30
  39. 39. Step 2, For DevicesInstead of forwarding the user, give them a code to use 31
  40. 40. Step 3 consumer key, request token, verifier Consumer Provider access token 32
  41. 41. Consumer: Step 3, Request an Access Token$oauth = new OAuth($config[consumer_key], $config[consumer_secret]);// request token, request token secret and verification all set// by earlier steps, and loaded into $configtry{ $oauth->setToken( $config[request_token], $config[request_token_secret]); $access = $oauth->getAccessToken($config[access_uri], null, $config[verification]);} catch (OAuthException $e) { echo $e->getMessage();} 33
  42. 42. Provider: Step 3, Generate Access TokenGenerate and store access token and secret, then return:echo "oauth_token=" . $tokens[oauth_token] . &oauth_token_secret= . $tokens[oauth_token_secret]; 34
  43. 43. Storing Access Tokens+---------------------+-------------+| Field | Type |+---------------------+-------------+| id | int(11) || consumer_key | varchar(30) || access_token | varchar(16) || access_token_secret | varchar(32) || user_id | int(11) || created_date | timestamp || last_used_date | datetime |+---------------------+-------------+ 35
  44. 44. Step 4 consumer key, access token, API request Consumer Provider API response 36
  45. 45. Consumer: Step 4, Subsequent Requests$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();} 37
  46. 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/ 38
  47. 47. Other OAuth Types
  48. 48. 3-legged OAuthSo far we have discussed 3-legged OAuth • Three parties are involved • Consumer • Provider • User 40
  49. 49. 2-legged OAuth2-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 41
  50. 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 42
  51. 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 spechttp://tools.ietf.org/html/draft-ietf-oauth-v2-15 43
  52. 52. Authorization GrantCan 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 44
  53. 53. Access Tokens and Refresh TokensRefresh 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 45
  54. 54. The State of OAuth • OAuth 1 • already in use • a faff! • OAuth 2 • still being finalised • different approach to same problem 46
  55. 55. Questions?
  56. 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 48
  57. 57. Thanks! Thanks! http://joind.in/3243/ @lornajane http://lornajane.net/ 49

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