Re: [OAUTH-WG] Question lengths in draft-sakimura-oauth-tcse-03

That too would suggest that the length limit be on code_challenge because
that's the parameter that will be on URIs getting passed around. The
code_verifier is sent directly in the POST body from client to AS.

On Tue, May 13, 2014 at 12:52 AM, Nat Sakimura <sakimura@gmail.com> wrote:

> +1 for octet. We used to have "bytes" in JW* so I used "bytes" here, while
> at the same time complaining in Jose that it should be "octet". JW* changed
> to "octet" but I failed to sync with it in the last few edits.
>
> I do not quite remember which platform, but the reason for the limit was
> that some platform had some limitations as to the length of the sting to be
> passed to it through URI and we did not want the challenges to be truncated
> by that limit.
>
> Best,
>
> Nat
>
>
> 2014-05-13 6:56 GMT+09:00 Brian Campbell <bcampbell@pingidentity.com>:
>
> And it'd give the AS some direct guidance on protecting itself from crazy
>> long code_challenge values rather than relying on the client not to do
>> something creative.
>>
>>
>> On Mon, May 12, 2014 at 3:54 PM, Brian Campbell <
>> bcampbell@pingidentity.com> wrote:
>>
>>> Right but that's why I'm asking why not just put the limit on
>>> code_challange rather than inferring it from code_verifyer + challenge
>>> algorithm, which probably bounds it but doesn't necessarily do so? It's not
>>> a big deal but would read more clearly, I think.
>>>
>>>
>>> On Mon, May 12, 2014 at 3:48 PM, John Bradley <ve7jtb@ve7jtb.com> wrote:
>>>
>>>> I think octets is more consistent with other JW* and OAuth specs.
>>>>
>>>> The code_challange is the same length as the code_verifyer or is a hash
>>>> of the code_verifyer so likely smaller than 128octets (43 ish for base64
>>>> 256 bit)
>>>>
>>>> Limiting the code_verifyer size sets the upper bound for
>>>> code_challange, unless someone comes up with a really creative code
>>>> challenge algorithm.
>>>>
>>>> I will talk to nat about changing it to octets when I see him tomorrow.
>>>>
>>>> John B.
>>>>
>>>> On May 12, 2014, at 11:15 PM, Derek Atkins <warlord@MIT.EDU> wrote:
>>>>
>>>> > Brian Campbell <bcampbell@pingidentity.com> writes:
>>>> >
>>>> >> I notice that code_verifier is defined as "high entropy
>>>> cryptographic random
>>>> >> string of length less than 128 bytes"  [1], which brought a few
>>>> questions and
>>>> >> comments to mind. So here goes:
>>>> >>
>>>> >> Talking about the length of a string in terms of bytes is always
>>>> potentially
>>>> >> confusing. Maybe characters would be an easier unit for people like
>>>> me to wrap
>>>> >> their little brains around?
>>>> >
>>>> > It depends if it really is characters or bytes.  For example there are
>>>> > many multi-byte UTF-8 characters, so if it really is bytes then saying
>>>> > characters is wrong because it could overflow.  So let's make sure we
>>>> > know what we're talking about.  Historically, if we're talking bytes
>>>> the
>>>> > IETF often uses the phrase "octets".  Would that be less confusing?
>>>> >
>>>> >> Why are we putting a length restriction on the code_verifier anyway?
>>>> It seems
>>>> >> like it'd be more appropriate to restrict the length of the
>>>> code_challenge
>>>> >> because that's the thing the AS will have to maintain somehow (store
>>>> in a DB
>>>> >> or memory or encrypt into the code). Am I missing something here?
>>>> >>
>>>> >> Let me also say that I hadn't looked at this document since its
>>>> early days in
>>>> >> draft -00 or -01 last summer but I like the changes and how it's
>>>> been kept
>>>> >> pretty simple for the common use-case while still allowing for
>>>> crypto agility/
>>>> >> extension. Nice work!
>>>> >>
>>>> >> [1]
>>>> http://tools.ietf.org/html/draft-sakimura-oauth-tcse-03#section-3.3
>>>> >
>>>> > -derek
>>>> >
>>>> >> _______________________________________________
>>>> >> OAuth mailing list
>>>> >> OAuth@ietf.org
>>>> >> https://www.ietf.org/mailman/listinfo/oauth
>>>> >
>>>> > --
>>>> >       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
>>>> >       Member, MIT Student Information Processing Board  (SIPB)
>>>> >       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
>>>> >       warlord@MIT.EDU                        PGP key available
>>>>
>>>>
>>>
>>>
>>> --
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>>> Brian Campbell
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>>>
>>
>>
>> --
>>    [image: Ping Identity logo] <https://www.pingidentity.com/>
>> Brian Campbell
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>>   @ bcampbell@pingidentity.com  [image: phone] +1 720.317.2061  Connect
>> with us…  [image: twitter logo] <https://twitter.com/pingidentity> [image:
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>>
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>
>
> --
> Nat Sakimura (=nat)
> Chairman, OpenID Foundation
> http://nat.sakimura.org/
> @_nat_en
>

-- 
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Brian Campbell
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