Subject: Re: [OAUTH-WG] Review draft-ietf-oauth-spop-00

From: Nat Sakimura <[email-masked]>
Date: Tue, 14 Oct 2014 18:12:18 +0900

Hi Eduardo, 

I have accepted all the "Suggestions" in the forthcoming 
version. You can see my private editing copy at 

https://bitbucket.org/Nat/oauth-spop/commits/f0f8599

to see how it has been incorporated. 

Best, 

Nat

On Wed, 03 Sep 2014 01:57:31 -0600
Eduardo Gueiros <[email-masked]> wrote:

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> Review of draft-ietf-oauth-spop-00
> 
> Gentleman, here are some notes on the OAuth SPOP Draft.
> 
> 
> Review Summary
> 
> A few grammar errors, no major flaws, some suggestions that could
> possibly make some passages clearer. Some questions as well.
> Also, providing a flow diagram would help clarify some of the
> interactions.
> 
> Abstract
> 
> > The OAuth 2.0 public client utilizing authorization code grant is 
> > susceptible to the code interception attack.
> 
> Suggestion for clearer reading:
> OAuth 2.0 public clients utilizing Authorization Code Grant (RFC 6749
> - - 4.1) are susceptible to an interception attack.
> 
> Introduction
> 
> Suggestion for clearer reading:
> > Public clients in OAuth 2.0 [RFC6749] is susceptible to the "code" 
> > interception attack.  The "code" interception attack is an attack 
> > that a malicious client intercepts the "code" returned from the 
> > authorization endpoint and uses it to obtain the access token.
> 
> Public clients utilizing OAuth 2.0 are susceptible to authorization
> code interception attack. A malicious client intercepts the
> authorization code returned from the authorization endpoint and uses
> it to obtain the access token.
> 
> Suggestion for clearer reading:
> > This is especially true on some smartphone platform in which the
> "code" is
> > returned to a redirect URI with a custom scheme as there can be 
> > multiple apps that can register the same scheme.
> 
> This is especially true on smartphones applications where the
> authorization code can be returned
> through custom URL Schemes where the same scheme can be registered by
> multiple applications.
> 
> Insert article before ‘dynamic’
> > To mitigate this attack, this extension utilizes dynamically
> > created cryptographically random key called 'code verifier'.
> 
> To mitigate this attack, this extension utilizes a dynamically created
> cryptographically random key called 'code verifier'.
> 
> Missing commas for context
> > The code verifier is created for every authorization request and
> > its transformed value called code challenge is sent to the
> > authorization server to obtain the authorization code.
> 
> The code verifier is created for every authorization request and its
> transformed value, called code challenge, is sent to the authorization
> server to obtain the authorization code.
> 
> 2 Terminology
> 2.1
> Question
> Random String: What constitutes ‘big enough entropy’? Shouldn’t
> minimum length be specified (e.g. 32 characters)?
> 
> 3 Protocol
> 3.1
> Question
> This paragraph states that the client must, through some mechanism,
> verify if the server supports this specification. Shouldn’t this
> mechanism be part of OAuth and therefore have an specification
> document on how to implement and perform the aforementioned
> verification?
> 
> Suggestion: Change MUST to SHOULD
> > The client that wishes to use this specification MUST stop
> > proceeding if the server does not support this extension.
> 
> I think a client can use this mechanism to implement a more secure
> transaction, but by verifying it, the client can be configured to
> continue performing the regular authorization grant if it chooses so.
> Hence, SHOULD instead of MUST.
> 
> 
> 3.3
> Question
> Goes with question on 2.1, why less than 128 bytes?
> 
> Suggestion
> > string of length less than 128 bytes
> string of length no less than 128 bytes
> 
> 
> Eduardo Gueiros
> Software Developer | Jive.com
> Jive Communications, Inc | egueiros at jive.com
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-- 
Nat Sakimura ([email-masked])
Nomura Research Institute, Ltd. 

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