Is there anyone who has problems changing it to a MUST? On 2015年2月18日(水) at 18:48 Hannes Tschofenig <hannes.tschofe...@gmx.net> wrote:
> I think that the "controlled environment" is a risky idea. I believe we > should definitely go for a MUST. > > On 02/18/2015 10:26 AM, Nat Sakimura wrote: > > Hi Hannes, > > > > The reason I have put SHOULD there instead of MUST is > > that there may be a valid reason not to in a controlled > > environment, and it does not interfere the interoperability. > > The deployment may opt to use other control than entropy, > > and SHOULD allows it while MUST does not. > > > > Having said that, if the WG is OK with a MUST there, > > I am fine with incorporating the proposed change. > > > > Cheers, > > > > Nat > > > > > > On Wed, 18 Feb 2015 09:43:30 +0100 > > Hannes Tschofenig <hannes.tschofe...@gmx.net> wrote: > > > >> Hi Nat, > >> > >> thanks for the quick response. > >> > >> I was hoping to see a statement like "The code verifier MUST have > >> enough entropy to make it impractical to guess the value." in the > >> text rather than the SHOULD. Given all the other statements in the > >> draft I am not sure what the should actually means. Under what > >> conditions would an implementer not provide enough entropy to make > >> guessing impractical? > >> > >> Ciao > >> Hannes > >> > >> On 02/18/2015 05:13 AM, Nat Sakimura wrote: > >>> Hi Hannes, > >>> > >>> I hereby confirm that I have submit the draft in full conformance > >>> with the provisions of BCP 78 and BCP 79. > >>> > >>> Re: Security Consideration (7.1) and section 4.1 > >>> > >>> The first part of the 7.1 is a non-normative prose explaining that > >>> the implementers got to make sure that the code verifier is hard to > >>> guessed or modeled. In a way, this is laying out the basic security > >>> property requirment on the code verifier. > >>> > >>> Then, it goes onto the implementation guideance that one need to > >>> use a cryptographic random number generator instead of relying on a > >>> rand() in some language that are not cryptographically random to > >>> generate 32-octet sequence. The same text is in 4.1 as well. > >>> > >>> We did not copy "code verifier SHOULD have enough entropy to make > >>> it impractical to guess the value" here because that looked > >>> needlessly repeating, but if you want, I have no objection in > >>> adding it to 7.1. > >>> > >>> Alternatively, in 7.1, after explaining the rationale, we can just > >>> point to 4.1 for the control and implementation guidance. > >>> > >>> Re: 32-octet > >>> > >>> We chose it because we are using SHA256 in generating the code > >>> challange. Having more entropy does not help us here, while having > >>> less octets increases the risk. > >>> > >>> Best, > >>> > >>> Nat > >>> > >>> > >>> > >>> On Tue, 17 Feb 2015 17:56:33 +0100 > >>> Hannes Tschofenig <hannes.tschofe...@gmx.net> wrote: > >>> > >>>> Hi Nat, John, Naveen, > >>>> > >>>> thanks a lot for your work on the document. > >>>> > >>>> I still need responses to this mail to complete the shepherd > >>>> writeup: > >>>> http://www.ietf.org/mail-archive/web/oauth/current/msg14100.html > >>>> > >>>> I definitely need the IPR confirmation. > >>>> > >>>> It would also be helpful to have someone who implemented the > >>>> specification as it currently is. I asked Brian and Thorsten for > >>>> clarification regarding their statements that they implemented > >>>> earlier versions of the spec. > >>>> > >>>> As a final remark I still believe that the text regarding the > >>>> randomness is still a bit inconsistent. Here are two examples: > >>>> > >>>> 1) In the Security Consideration you write that "The security model > >>>> relies on the fact that the code verifier is not learned or > >>>> guessed by the attacker. It is vitally important to adhere to > >>>> this principle. " > >>>> > >>>> 2) In Section 4.1 you, however, write: "NOTE: code verifier SHOULD > >>>> have enough entropy to make it impractical to guess the value. It > >>>> is RECOMMENDED that the output of a suitable random number > >>>> generator be used to create a 32-octet sequence." > >>>> > >>>> There is clearly a long way from a SHOULD have enough entropy to > >>>> the text in the security consideration section where you ask for > >>>> 32 bytes entropy. > >>>> > >>>> It is also not clear why you ask for 32 bytes of entropy in > >>>> particular. > >>>> > >>>> Ciao > >>>> Hannes > >>>> > >>> > >>> > >> > > > > > > _______________________________________________ > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth >
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