Re: [Unbearable] I-D Action: draft-ietf-tokbind-https-10.txt

[Denis <[e-mail]>]

Nick,

A person reading draft-ietf-tokbind-https will not necessarily also read 
draft-ietf-tokbind-protocol.

So, I believe it is necessary to warn again the reader in the Security 
Considerations section.
Duplication of the text you quoted in that section would address my concern.

You said that the fact that clients could collude is a*property *of the 
Token Binding protocol.
I would rather say that it is a *limitation *or a *deficiency *of the 
Token Binding protocol.

Denis

> draft-ietf-tokbind-protocol-15 already has language which says "The
> Token Binding protocol does not prevent cooperating clients from
> sharing a bound token.  A client could intentionally export a bound
> token with the corresponding Token Binding private key, or perform
> signatures using this key on behalf of another client." I don't think
> we need any additional language in this draft regarding client
> collusion. That clients could collude is a property of the Token
> Binding protocol, so it doesn't need to be repeated in this
> application profile for using Token Binding.
>
> On Fri, Jul 21, 2017 at 2:21 AM, Denis <[e-mail]> wrote:
>> This ID is still lacking to indicate that  this mechanism will be
>> ineffective in case of a collusion between clients.
>>
>> This should be clearly indicated in the Security Considerations section.
>>
>> Denis
>>
>>
>>> A New Internet-Draft is available from the on-line Internet-Drafts
>>> directories.
>>> This draft is a work item of the Token Binding WG of the IETF.
>>>
>>>           Title           : Token Binding over HTTP
>>>           Authors         : Andrei Popov
>>>                             Magnus Nyström
>>>                             Dirk Balfanz
>>>                             Adam Langley
>>>                             Nick Harper
>>>                             Jeff Hodges
>>>          Filename        : draft-ietf-tokbind-https-10.txt
>>>          Pages           : 22
>>>          Date            : 2017-07-21
>>>
>>> Abstract:
>>>      This document describes a collection of mechanisms that allow HTTP
>>>      servers to cryptographically bind security tokens (such as cookies
>>>      and OAuth tokens) to TLS connections.
>>>
>>>      We describe both first-party and federated scenarios.  In a first-
>>>      party scenario, an HTTP server is able to cryptographically bind the
>>>      security tokens it issues to a client, and which the client
>>>      subsequently returns to the server, to the TLS connection between the
>>>      client and server.  Such bound security tokens are protected from
>>>      misuse since the server can generally detect if they are replayed
>>>      inappropriately, e.g., over other TLS connections.
>>>
>>>      Federated token bindings, on the other hand, allow servers to
>>>      cryptographically bind security tokens to a TLS connection that the
>>>      client has with a different server than the one issuing the token.
>>>
>>>      This Internet-Draft is a companion document to The Token Binding
>>>      Protocol.
>>>
>>>
>>> The IETF datatracker status page for this draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-tokbind-https/
>>>
>>> There are also htmlized versions available at:
>>> https://tools.ietf.org/html/draft-ietf-tokbind-https-10
>>> https://datatracker.ietf.org/doc/html/draft-ietf-tokbind-https-10
>>>
>>> A diff from the previous version is available at:
>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-tokbind-https-10
>>>
>>>
>>> Please note that it may take a couple of minutes from the time of
>>> submission
>>> until the htmlized version and diff are available at tools.ietf.org.
>>>
>>> Internet-Drafts are also available by anonymous FTP at:
>>> ftp://ftp.ietf.org/internet-drafts/
>>>
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>>
>>
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