OAuth 2.0

Josh Kerr

February 2, 2016

About Me

Agenda

  • Background

  • OAuth 2.0 Concepts

  • OAuth 2.0 Flows

  • Extensions

Why OAuth?

Example Scenario

Example Scenario

So what's the problem?

Enter OAuth!

Enter OAuth!

  • Open framework for security

  • No more password exchange

  • Delegated access

  • 3rd Party apps store a token

  • Limited and scope

Brief History

OAuth 1.0

  • Shared secrets between endpoints

  • 3 overlapping flows

  • Confusing spec

OAuth 2.0

  • Relies on TLS/SSL

  • Identifiable flows

  • Clearly defined roles 

Real World Examples

The Basics

Authentication

Authorization

vs.

Roles

  • Resource Owner - The user

  • Resource Server - The API

  • Authorization Server - Issues tokens

  • Client - The application

Scopes

  • Similar to permissions

  • Limits the usefulness of the token

  • Users consent via UI (when shown)

Client Registration

  • Clients register with the Authorization Server

  • Confidential vs. Public

Access Token

  • Short lived

  • Reference vs. Value

  • Format is up to you

  • Bearer vs. MAC

Refresh Token

  • Longer lived

  • Used with client credentails to obtain an access token

Authorization Code

Implicit

Client Resource Owner

Client Credential

Authorization Code

Authorization Code

  • Most common form of OAuth

  • Typically Server 2 Server

  • Confidential client

  • Tokens are refresh-able

Client Application

Auth Server

Resource Server

Resource Owner

Request token

Login and approve

Authorization code

Exchange code for a token

Access Token

Call secured service with Access Token

{
    "access_token": "T9cE5asGnuyYCCqIZFoWjFHl",
    "expires_in": 3600,
    "token_type": "bearer",
    "refresh_token": "J7rxTiWOHMoSC1isKZgCUfGMinKBDLZWP9BgR"
}
POST https://myapp.com/api/oauth2/token

    grant_type=authorization_code&code=123456abcdef&
    client_id=MY_CLIENT_ID&client_secret=MY_CLIENT_SECRET
GET https://myapp.com/api/oauth2/authorize?response_type=code&
    client_id=MY_CLIENT_ID&state=security_state&
    redirect_url=https://jokerr.net/oauth
https://jokerr.net/oauth?code=123456abcdef&state=security_state
GET /resource HTTP/1.1
Host: myapp.com
Authorization: Bearer T9cE5asGnuyYCCqIZFoWjFHl

Implicit

  • Typically browser based

  • Client secret is assumed to be compromised

  • Tokens are not refreshable

Implicit

Client Application

Auth Server

Resource Server

Resource Owner

Request token

Login and approve

Access Token

Call secured service with Access Token

GET https://myapp.com/authorize?response_type=token&
    client_id=MY_CLIENT_ID&
    redirect_url=https://jokerr.net/oauth
https://jokerr.net/oauth?access_token=T9cE5asGCCqIZFo
    &token_type=bearer

Client Resource Owner

  • Exchange your credentials for a token

  • Confidential client usually created by the service provider

  • Tokens are refreshable

Client Resource Owner

Client Application

Auth Server

Resource Server

Resource Owner

Request Token with username/password

Access Token

Call secured service with Access Token

Validate credentials

POST https://myapp.com/api/oauth2/token
    grant_type=password&
    username=jokerr&
    password=12345&
    client_id=MY_CLIENT_ID
{
    "access_token": "T9cE5asGnuyYCCqIZFoWjFHl",
    "expires_in": 3600,
    "token_type": "bearer",
    "refresh_token": "J7rxTiWOHMoSC1isKZgCVJ9bKBDLZWP9BgR"
}

Client Credential

  • Actions are not performed on behalf of a user (think batch)

  • Tokens are not refreshable

Client Resource Owner

Client Application

Auth Server

Resource Server

Request Token with client credentials

Access Token

Call secured service with Access Token

Validate credentials

POST https://myapp.com/api/oauth2/token
    grant_type=client_credentials&
    client_id=MY_CLIENT_ID&
    client_secret=MY_CLIENT_SECRET
{
    "access_token": "T9cE5asGnuyYCCqIZFoWjFHl",
    "expires_in": 3600,
    "token_type": "bearer"
}

JWT Token

JWT

JSON Web Token is a means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is digitally signed using JSON Web Signature (JWS) and/or encrypted using JSON Web Encryption (JWE).

header.payload.signature
  • JSON object

  • Defined structure and keys (claims)

  • Can be signed (JWS)

  • Can be encrypted (JWE)

JWT

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
.
eyJzdWIiOiJKb2tlcnIiLCJuYW1lIjoiSm9zaCBLZXJyIiwiYXVkIjoiU0FUIEpVRyJ9
.
VUJOunV-K9lOqjf-jAr_pGZIt6ja3fNXXS-v8vmyx7A
{
  "alg": "HS256",
  "typ": "JWT"
}
.
{
  "sub": "Jokerr",
  "name": "Josh Kerr",
  "aud": "SAT JUG",
  "iat": 1453342985,
  "exp": 1454379784
}
.
HMACSHA256(
  base64UrlEncode(header) + "." +
  base64UrlEncode(payload),
  secret
)

JWT Demo

JWT Token...

Who Cares?

JWT

  • Similar to a SAML token but lighter and compact 

  • Great for authentication scenarios or information exchanges

  • Can be passed over headers or querystring

OAuth + JWT

  • Extension of the spec

  • Can be used for client authentication

  • Can be the access token

{
  "iss": "https://idp.jokerr.net",
  "sub": "jokerr",
  "aud": "https://satjug.slack.com",
  "iat": 1453342985,
  "exp": 1454379784,
  "jti": "8ce244c2-9090-43e3-8aaf-2632a6daf33b"
}
POST https://myapp.com/api/oauth2/token
grant_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer
&assertion=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.
eyJpc3MiOiJodHRwczovL2lkcC5qb2tlcn[...omitted...]zYiJ9.
WgIONUSAR7L5CmbtwbZBmQaYFBQrMBInS5PbmS_vW-w

OpenID Connect

What's the problem?

  • Access Token doesn't prove authentication

  • No standardized user indentification

  • OAuth 2.0 + Identity Token

  • OAuth is an authorization framework

  • Identity Token (JWT) for authentication

OpenID connect

Java Options?

Apache Oltu

Spring Security OAuth

Refrences

Questions?

oauth

By Josh Kerr

oauth

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