Re: [MLS] Question regarding ClientInitKey message format

Pascal Junod <pascalj@snap.com> Thu, 03 October 2019 08:09 UTC

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From: Pascal Junod <pascalj@snap.com>
Date: Thu, 3 Oct 2019 10:09:20 +0200
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To: Messaging Layer Security WG <mls@ietf.org>
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Subject: Re: [MLS] Question regarding ClientInitKey message format
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Thank you Benjamin and Richard for your quick and clear answers ! I had
missed the update in the master version and indeed, ยง3.4 of RFC 8446 is
clear about the byte lengths.

On Wed, Oct 2, 2019 at 11:38 PM Richard Barnes <rlb@ipv.sx>; 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.
>
> 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 <cryptopathe@gmail.com>; 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
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