Re: [Webpush] Kathleen Moriarty's No Objection on draft-ietf-webpush-vapid-03: (with COMMENT)

[Kathleen Moriarty <[e-mail]>]

Hi Martin,

On Tue, Aug 15, 2017 at 9:11 PM, Martin Thomson
<[e-mail]> wrote:
> On 16 August 2017 at 04:50, Kathleen Moriarty
> <[e-mail]> wrote:
>> In section 3, it seems that you are just signing the JWK and that seems fine
>> from the text and the purpose listed - origin server authentication.
>>
>> Then in section 3.2, there's a reference to I-D.ietf-webpush-encryption saying,
>> "An application server MUST select a different
>>    private key for the key exchange".  This makes me think that encryption is
>>    used as well, but I think it would be helpful to see the point made more
>>    clear here or in the security considerations section.  Is confidentiality
>>    provided/required or just integrity for this draft?
>
> There are two separate mechanisms.  -encryption sends a message to the
> user agent.  That message has confidentiality and integrity protection
> - the push service can't see or modify that message.  In the envelope
> of that message, we have this JWT.  The confidentiality/integrity
> protection for that is HTTPS.  Confidentiality is required to prevent
> theft of the token, as stated in the security considerations.  What I
> now realize is that I didn't actually reiterate the requirement for
> HTTPS from 8030.
>
>   https://github.com/webpush-wg/webpush-vapid/pull/41

Thanks for adding text, there wasn't mention of confidentiality being
required  or HTTPS in the version I read, so that is a helpful
addition.
>
> The text you cite is included specifically to maybe prevent someone
> from incorrectly using the same key for signing (in -vapid) and
> encryption (in -encryption).  Unfortunately, this specific type of
> misuse is possible in a lot of codebases and does happen.

OK, if it's possible to edit the cited text to make it more clear, I
think that would be helpful to any implementer that comes along later.



-- 

Best regards,
Kathleen