What's New in OAuth 2.1 Aaron Parecki Senior Security Architect, Okta API Days Australia • September 2020 

@aaronpk September 2020 oauth.net/2 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials Grant Types 

@aaronpk September 2020 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials Grant Types RFC6750 Bearer Tokens Token Usage Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk September 2020 

@aaronpk September 2020 OAuth Server OAuth Client Passing Data via the Front Channel Did they catch 
 it? Did someone else 
 steal it? Is this really 
 from the real 
 OAuth server? 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk September 2020 

@aaronpk September 2020 https://example.com https://app.example.com https://auth.example GET / HTML, CSS, etc POST /token access token CORS 

@aaronpk September 2020 caniuse.com/cors 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk September 2020 OAuth 2.0 for Browser-Based Apps 

@aaronpk September 2020 OAuth 2.0 for Browser-Based Apps 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs PKCE for confidential clients Security BCP 

@aaronpk September 2020 Password oauth.net/2/oauth-best-practice 

@aaronpk September 2020 Password oauth.net/2/oauth-best-practice • Added to OAuth to enable migrating applications from HTTP Basic Auth or using a stored password to OAuth 

@aaronpk September 2020 OAuth 2.0 Security BCP • All OAuth clients MUST use PKCE with the authorization code flow • Password grant MUST NOT be used • Use exact string matching for redirect URIs • No access tokens in query strings • Refresh tokens for public clients must be 
 sender-constrained or one-time use oauth.net/2/oauth-best-practice 

@aaronpk September 2020 RFC6749 RFC6750 CLIENT TYPE AUTH GRANT TYPE RFC6819 RFC7009 RFC7592 RFC7662 RFC7636 RFC7591 RFC7519 BUILDING YOUR APPLICATION RFC8252 OIDC RFC8414 STATE TLS CSRF UMA 2 FAPI RFC7515 RFC7516 RFC7517 RFC7518 TOKEN POP SECURITY BCP CIBA HTTP SIGNING MUTUAL TLS SPA BCP JARM JAR TOKEN DPOP PAR 

@aaronpk September 2020 OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs PKCE for confidential clients Security BCP 

@aaronpk September 2020 OAuth 2.1 Authorization Code Client Credentials +PKCE Tokens in HTTP Header Tokens in POST Form Body 

OAuth 2.1 oauth.net/2.1 

@aaronpk September 2020 OAuth 2.1 Consolidate the OAuth 2.0 specs,
 adding best practices, 
 removing deprecated features Capture current best practices in OAuth 2.0 under a single name Add references to extensions that didn't exist when OAuth 2.0 was published 

@aaronpk September 2020 OAuth 2.1 No new behavior defined by OAuth 2.1 Non-Goals: Don't include anything experimental, 
 in progress or not widely implemented 

@aaronpk September 2020 OAuth 2.1 Authors: Dick Hardt, Aaron Parecki, Torsten Lodderstedt • OAuth 2.1 is a consolidation of: 
 OAuth 2.0 (RFC6749), Native Apps BCP (RFC8252), PKCE (RFC7636), Browser-Based Apps BCP (draft), Security BCP (draft), 
 Bearer Tokens (RFC6750) • Grant types defined: Authorization Code with PKCE, Client Credentials • Exact redirect URI matching • No Bearer tokens in query strings • Refresh tokens for SPAs must be sender-constrained or one-time use • Implicit and password grants are omitted 

@aaronpk September 2020 OAuth 2.1 Client Types Public Confidential 

@aaronpk September 2020 OAuth 2.1 Client Types Public Confidential Credentialed 

@aaronpk September 2020 Credentialed Client This distinction already exists in OAuth 2.0! OAuth 2.0: If the client type is confidential or the client was issued client credentials, the client MUST authenticate... OAuth 2.1: Confidential or credentialed clients MUST authenticate... 

@aaronpk September 2020 Credentialed Client • A client that has credentials, but whose identity is not confirmed • e.g. a client that obtains a client secret via dynamic client registration 

@aaronpk September 2020 OAuth 2.1 oauth.net/2.1 tools.ietf.org/html/draft-ietf-oauth-v2-1 Recently adopted by the OAuth Working Group 

Thank you! @aaronpk aaronpk.com oauth.wtf