Intro to OAuth - Speaker Deck

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Intro to OAuth Matt Frost @shrtwhitebldguy https://joind.in/10630

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Who Am I? • Senior Engineer - Synacor • Author • OSS Contributor • Mentoring Proponent • Podcast co-host

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What is OAuth?

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Tokens

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Statelessness

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Applications have tokens too

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So what you’re saying is…

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Yep!

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Tokens can be stolen though

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This is bad

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Good news though!

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There are different versions

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Technically OAuth 1 is deprecated

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Just like the mysql extension You’re probably going to run into it at some point anyway….

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So here’s the plan

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OAuth 1.0 Client

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So we need tokens, right?

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Token Deﬁnitions

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Consumer Tokens

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Temporary Credentials

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Access Tokens

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Token Request Flow

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Super simple right? https://developer.yahoo.com/oauth/guide/oauth-auth-ﬂow.html

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Let’s break this down, eh?

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You need an application

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Request the temporary tokens

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If you signed it right…

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You’ll have temporary credentials

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You now use these to request Access Tokens

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If you sign that request right…

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You’ll have your actual Access Tokens!

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You can store them in a session or database and use them now!

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Remember all that signing talk?

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This is the hardest part…

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Base String

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$this->getNonce(),! ! 'oauth_callback' => $this->getCallback(),! ! 'oauth_signature_method' => $this->getSignatureMethod(),! ! 'oauth_timestamp' => time(),! ! 'oauth_consumer_key' => $this->getConsumerKey(),! ! 'oauth_token' => '',! ! 'oauth_version' => '1.0',! ];

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HTTP Method and URI

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Let’s see how this actually works

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$this->getNonce(),! 'oauth_callback' => $this->getCallback(),! 'oauth_signature_method' => $this->getSignatureMethod(),! 'oauth_timestamp' => time(),! ‘oauth_consumer_key' => $this->getConsumerKey(),! 'oauth_token' => ‘',! 'oauth_version' => '1.0',! ];! ! $tempArray = [];! ksort($params);! foreach($params as $key => $value) {! ! $tempArray = $key . '=' . rawurlencode($value);! }! ! $baseString = $httpMethod . '&';! $baseString .= rawurlencode($uri) . '&';! $baseString .= implode('&', $tempArray);

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Composite Key This is way easier…

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Cram the 2 secrets together…

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$consumer_secret = 'VERYSECRETZ';! $access_secret = 'SUCHSECURITY';! ! $composite_key = rawurlencode($consumer_secret) .'&'. rawurlencode($access_secret);

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Signing with HMAC-SHA1

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$signature = base64_encode(hash_hmac(! ! 'sha1',! ! $baseString,! ! $compositeKey,! ! true! )); Here’s your signature!

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There are other signature types but…

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However…

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Authorization Header

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$params = [! 'oauth_nonce' => $this->getNonce(),! ! 'oauth_callback' => $this->getCallback(),! ! 'oauth_signature_method' => $this->getSignatureMethod(),! ! 'oauth_timestamp' => time(),! ! 'oauth_consumer_key' => $this->getConsumerKey(),! ! 'oauth_token' => '',! ! 'oauth_version' => '1.0',! ];! ! $params[‘oauth_signature’] = $signature; You probably remember this array?

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$header = “Authorization: OAuth “;! $tempArray = [];! ! foreach($params as $key => $value) {! $tempArray[] = $key . ‘=“‘. rawurlencode($value);! }! ! $header .= implode(‘,’, $tempArray);! We’ve seen similar code before…

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Authorization: OAuth oauth_consumer_key="xxxxxxxxx", oauth_nonce="fklj2324kljfksjf234k", oauth_signature="8xJAdrE00wGH21w87P 6N%2F8c0XZfeo%3D", oauth_signature_method="HMAC-SHA1", oauth_timestamp="1399488541", oauth_token="xxxxxxxxx", oauth_version="1.0" This is the ﬁnal result

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Whew! That was some work

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OAuth 1.0 Server

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Token Generation

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Recreate the signature with the info you received

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If they match, they win!

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If not…

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Access Control…

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OAuth 2 Client

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Good news!

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No signatures

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Must use SSL/TLS

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Consumer Credentials

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Access Token

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Grants

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Authorization Code Grant

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Authorization example - Foursquare

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http://foursquare.com/oauth2/authenticate? client_id=XXXXXXXXX&response_type=code&redirect_uri=htt p://oauth.dev/examples/Foursquare/callback.php

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Token Request

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http://oauth.dev/examples/ Foursquare/callback.php? code=

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https://foursquare.com/oauth2/access_token? client_id=&client_secret=&code=

&callback=http://oauth.dev/examples/
Foursquare/callback.php&grant_type=authorization_code

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If you can use this, you should

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Implicit Grant

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http://foursquare.com/oauth2/authenticate? client_id=XXXXXXXXX&response_type=token&redirect_uri=ht tp://oauth.dev/examples/Foursquare/callback.php

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Resource Owner Credentials Grant

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Client Credentials Grant

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Scopes

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“Scopes” in OAuth 1

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Scopes in OAuth 2

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Important Note on Scopes

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Provides an ACL Framework

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Refresh Tokens

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Same Scope

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OAuth 2 Server

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Issuing Tokens

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Should I Support All The Grants?

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Maybe…

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Authorization/Implicit Grants

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Storing Token Info

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Scopes

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Reading Tokens

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Query String, Header, Both?

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A Caution Against Rolling Your Own

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RFCs OAuth 1 RFC 5849 - http://tools.ietf.org/html/rfc5849 OAuth 2 RFC 6749 - http://tools.ietf.org/html/rfc6749