Re: [OAUTH-WG] ECDH-1PU encryption algorithm

I'm supportive of this work.

It is not clear that it is in the charter of the OAuth WG.

On Mon, Aug 10, 2020 at 9:01 AM Filip Skokan <panva.ip@gmail.com> wrote:

> Hi Neil,
>
> I'm interested in seeing both AES SIV and ECDH-1PU for JOSE. Not sure how
> to go about it tho since JOSE is a concluded WG.
>
> Out of curiosity, why is it a concluded WG? Did IETF/JOSE WG not consider
> the need to further maintain/expand the JOSE algorithms as time goes on?
>
> S pozdravem,
> *Filip Skokan*
>
>
> On Mon, 10 Aug 2020 at 10:29, Neil Madden <neil.madden@forgerock.com>
> wrote:
>
>> Thanks Vladimir,
>>
>> Responses below
>>
>> > On 8 Aug 2020, at 10:40, Vladimir Dzhuvinov <vladimir@connect2id.com>
>> wrote:
>> >
>> > Hi Neil,
>> >
>> > I definitely like the elegance of the proposed alg for JOSE, it provides
>> > something that isn't currently available in the various classes of algs
>> > made standard in JOSE.
>> >
>> > I also wanted to ask what's happening with AES SIV for JOSE, if there's
>> > traction / feedback / support there as well?
>> >
>> > https://tools.ietf.org/html/draft-madden-jose-siv-mode-02
>>
>> Thanks for bringing this up. I’ve not received much feedback about this
>> one, and I haven’t been very good at pushing it. If there is interest then
>> I’d certainly be interested in bringing this forward too.
>>
>> That draft might be a better fit for eg the COSE WG though, which could
>> then also register identifiers for JOSE. What do you think?
>>
>> >
>> > Vladimir
>> >
>> >
>> >>> On 05/08/2020 13:01, Neil Madden wrote:
>> >> Hi all,
>> >> You may remember me from such I-Ds
>> >> as https://tools.ietf.org/html/draft-madden-jose-ecdh-1pu-03, which
>> >> proposes adding a new encryption algorithm to JOSE. I’d like to
>> >> reserve a bit of time to discuss it at one of the upcoming interim
>> >> meetings.
>> >> The basic idea is that in many cases in OAuth and OIDC you want to
>> >> ensure both confidentiality and authenticity of some token - for
>> >> example when transferring an ID token containing PII to the client
>> >> through the front channel, or for access tokens intended to be handled
>> >> by a specific RS without online token introspection (such as the JWT
>> >> access token draft). If you have a shared secret key between the AS
>> >> and the client/RS then you can use symmetric authenticated encryption
>> >> (alg=dir or alg=A128KW etc). But if you need to use public key
>> >> cryptography then currently you are limited to a nested
>> >> signed-then-encrypted JOSE structure, which produces much larger token
>> >> sizes.
>> >> The draft adds a new “public key authenticated encryption” mode based
>> >> on ECDH in the NIST standard “one-pass unified” model. The primary
>> >> advantage for OAuth usage is that the tokens produced are more compact
>> >> compared to signing+encryption (~30% smaller for typical access/ID
>> >> token sizes in compact serialization). Performance-wise, it’s roughly
>> >> equivalent. I know that size concerns are often a limiting factor in
>> >> choosing whether to encrypt tokens, so this should help.
>> >> In terms of implementation, it’s essentially just a few extra lines of
>> >> code compared to an ECDH-ES implementation. (Some JOSE library APIs
>> >> might need an adjustment to accommodate the extra private key needed
>> >> for encryption/public key for decryption).
>> >> I’ve received a few emails off-list from people interested in using it
>> >> for non-OAuth use-cases such as secure messaging applications. I think
>> >> these use-cases can be accommodated without significant changes, so I
>> >> think the OAuth WG would be a good venue for advancing this.
>> >> I’d be interested to hear thoughts and discussion on the list prior to
>> >> any discussion at an interim meeting.
>> >> — Neil
>>
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