Securing RESTful Payment APIs Using OAuth 2


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Constructing a successful and simple API is the lifeblood of your developer community, and REST is a simple standard through which this can be accomplished. As we construct our API and need to secure the system to authenticate and track applications making requests, the open standard of OAuth 2 provides us with a secure and open source method of doing just this.

In this talk, we will explore REST and OAuth 2 as standards for building out a secure API infrastructure, exploring many of the architectural decisions that PayPal took in choosing variations in the REST standard and specific implementations of OAuth 2.

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  • This is where REST and OAuth 2 come in
  • Working with HATEOASHypermedia as the Engine of Application State("hate -o's") or "hate yo' ass"
  • Constructor
  • The cURL method for HTTP requests
  • Securing RESTful Payment APIs Using OAuth 2

    1. 1. Securing RESTful Payment APIs Using OAuth 2 Jonathan LeBlanc Principal Developer Evangelist (PayPal) Github: Twitter: @jcleblanc
    2. 2. The Ultimate Decision Security Usability
    3. 3. What a RESTful API isn’t Our API is RESTful, we support GET, PUT, POST, and DELETE requests No…actually you just support HTTP…like the rest of the web.
    4. 4. What a RESTful API is Honor HTTP request verbs Use proper HTTP status codes No version numbering in URIs Return format via HTTP Accept header Double Rainbow: Discovery via HATEOAS
    5. 5. Does Anyone Actually Do That?Very few APIsfollow pragmaticREST principles
    6. 6. "links": [{ "href": " payment/PAY-6RV75EKEYSZ6Y", "rel": "self", "method": "GET" },{ "href": " cmd=_express-checkout&token=EC-6019609", "rel": "approval_url", "method": "REDIRECT" },{ "href": " payment/PAY-6RV75EKEYSZ6Y/execute", "rel": "execute", "method": "POST" }]
    7. 7. When You Need Access Security
    8. 8. A Few Different Flavors of Usage User login (authentication) User Involvement (authorization) Application only (bearer tokens)
    9. 9. Our App Usage: Bearer Tokens
    10. 10. Making Your Definitions <?php define("CLIENT_ID", "YOUR CLIENT ID"); define("CLIENT_SECRET", "YOUR CLIENT SECRET"); define("URI_SANDBOX", ""); define("URI_LIVE", ""); ?>
    11. 11. class paypal{ private $access_token; private $token_type; public function __construct(){ $postvals = "grant_type=client_credentials"; $uri = URI_SANDBOX . "oauth2/token"; $auth_response = self::curl($uri, POST, $postvals, true); $this->access_token = $auth_response[body]->access_token; $this->token_type = $auth_response[body]->token_type; } …}
    12. 12. private function curl($url, $method = GET, $postvals = null, $auth = false){ $ch = curl_init($url); if ($auth){ $headers = array("Accept: application/json", "Accept-Language: en_US"); curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC); curl_setopt($ch, CURLOPT_USERPWD, CLIENT_ID . ":" .CLIENT_SECRET); } else { $headers = array("Content-Type:application/json", "Authorization:{$this->token_type} {$this->access_token}"); }
    13. 13. $options = array( CURLOPT_HEADER => true, CURLINFO_HEADER_OUT => true, CURLOPT_HTTPHEADER => $headers, CURLOPT_RETURNTRANSFER => true, CURLOPT_VERBOSE => true, CURLOPT_TIMEOUT => 10 ); if ($method == POST){ $options[CURLOPT_POSTFIELDS] = $postvals; $options[CURLOPT_CUSTOMREQUEST] = $method; } curl_setopt_array($ch, $options); $response = curl_exec($ch); return $response;}
    14. 14. Making a Call with the Tokenpublic function process_payment($request){ $postvals = $request; $uri = URI_SANDBOX . "payments/payment"; return self::curl($uri, POST, $postvals);}
    15. 15. The Last Considerations REST and OAuth are specifications, not religions Don’t alienate your developers with security Open source is your friend
    16. 16. Thank You! Questions? Jonathan LeBlanc Principal Developer Evangelist (PayPal) Github: Twitter: @jcleblanc