Subject: [MLS] Question regarding ClientInitKey message format

From: Pascal Junod <[email-masked]>
Date: Tue, 1 Oct 2019 17:30:42 +0200

Hello,

I am new to that list, so please accept my apologies in advance for any
wrong doings with respect to the list etiquette !

I am currently reading draft-07 (Aug. 13, 2019) and something is not clear
to me with respect to the ClientInitKey format defined in section 7. The
array of ciphersuites cipher_suites is expected to have a length of 0 to
255 ciphersuites, while the array of public keys init_keys is expected to
have between one and 65535 public keys. At the same time, an above
paragraph says that the init_array MUST have the same length as the
cipher_suites array. Shouldn't both of them having a length <1,255> ? Or
what did I misunderstand?

Best,

Pascal

---

From: Benjamin Beurdouche <[email-masked]>
Date: Wed, 2 Oct 2019 17:11:24 +0100

Hi Pascal,

If you look at the latest version of the draft (master) which is available on Github [0]
we moved away from having multiple cipher suites advertized in the ClientInitKey
to have only one ciphersuite [1], hence solving that issue at the same time… :)

Let me/us know if you have any questions…

Best,
Benjamin

[0] https://github.com/mlswg/mls-protocol/blob/master/draft-ietf-mls-protocol.md
[1] https://github.com/mlswg/mls-protocol/pull/204/files

> On Oct 1, 2019, at 4:30 PM, Pascal Junod <[email-masked]> wrote:
> 
> Hello, 
> 
> I am new to that list, so please accept my apologies in advance for any wrong doings with respect to the list etiquette ! 
> 
> I am currently reading draft-07 (Aug. 13, 2019) and something is not clear to me with respect to the ClientInitKey format defined in section 7. The array of ciphersuites cipher_suites is expected to have a length of 0 to 255 ciphersuites, while the array of public keys init_keys is expected to have between one and 65535 public keys. At the same time, an above paragraph says that the init_array MUST have the same length as the cipher_suites array. Shouldn't both of them having a length <1,255> ? Or what did I misunderstand?
> 
> Best, 
> 
> Pascal
> _______________________________________________
> MLS mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/mls

---

From: Richard Barnes <[email-masked]>
Date: Wed, 2 Oct 2019 22:38:00 +0100

In addition to what Benjamin said, I think you've misunderstood the meaning
of the length indications.  The lengths indicate the size in *bytes*, not
in *entries*.  So the ciphersuites field can hold 128 2-byte ciphersuites,
and the init_keys can hold however many public keys will fit in 65535 bytes.

But as Benjamin said, this has all been obsoleted by more recent changes.

--Richard

On Wed, Oct 2, 2019 at 4:17 PM Pascal Junod <[email-masked]> wrote:

> I am currently reading draft-07 (Aug. 13, 2019) and something is not
> clear to me with respect to the ClientInitKey format defined in section
> 7. The array of ciphersuites cipher_suites is expected to have a length
> of 0 to 255 ciphersuites, while the array of public keys init_keys is
> expected to have between one and 65535 public keys. At the same time, an
> above paragraph says that the init_array MUST have the same length as the

---

From: Pascal Junod <[email-masked]>
Date: Thu, 3 Oct 2019 10:09:20 +0200

Thank you Benjamin and Richard for your quick and clear answers ! I had
missed the update in the master version and indeed, §3.4 of RFC 8446 is
clear about the byte lengths.

On Wed, Oct 2, 2019 at 11:38 PM Richard Barnes <[email-masked]> wrote:

> In addition to what Benjamin said, I think you've misunderstood the
> meaning of the length indications.  The lengths indicate the size in
> *bytes*, not in *entries*.  So the ciphersuites field can hold 128 2-byte
> ciphersuites, and the init_keys can hold however many public keys will fit
> in 65535 bytes.
>
>> above paragraph says that the init_array MUST have the same length as
>> the cipher_suites array. Shouldn't both of them having a length <1,255>
>> ? Or what did I misunderstand?
>>
>> Best,
>>
>> Pascal
>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ietf.org_mailman_listinfo_mls&d=DwMFaQ&c=ncDTmphkJTvjIDPh0hpF_w&r=Ifbwlzxh3jRRAPiBazmj6w&m=mn-PKj1DJNfK2Rh9tm9kieCLTE80UiEIi1WgTqcoI88&s=7OSo9t-7f6c0oSTT_K93tm093Yw4WQb-1_a3uqKEMAc&e=>
>>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ietf.org_mailman_listinfo_mls&d=DwICAg&c=ncDTmphkJTvjIDPh0hpF_w&r=Ifbwlzxh3jRRAPiBazmj6w&m=mn-PKj1DJNfK2Rh9tm9kieCLTE80UiEIi1WgTqcoI88&s=7OSo9t-7f6c0oSTT_K93tm093Yw4WQb-1_a3uqKEMAc&e=
>