[zeromq-dev] CurveZMQ: 16 vs 8 bit nonces

[Pieter Hintjens]

I don't think it's about importance of different keys. The short nonce
works better as a counter, and 8 bytes is sufficient. The long nonce
could be a counter, but that's extra work to implement, and a *good*
random number generator is ideal. 16 bytes may be overkill, however
it's inherited from CurveCP and I don't argue with that design.

On Wed, Jul 2, 2014 at 9:29 PM, Diego Duclos
<diego.duclos at palmstonegames.com> wrote:
> Thanks a lot Pieter, I had missed that section.
> I still miss the why somewhat though, is this purely to save computing power
> as the transient keys are less important to protect then the permanent keys
> ? And thus use shorter nonces.
>
>
> On Wed, Jul 2, 2014 at 9:26 PM, Pieter Hintjens <ph at imatix.com> wrote:
>>
>> It says, in the RFC: "We use two kinds of nonces in CurveZMQ. A long
>> nonce protects permanent keys, and is 16 octets from a good random
>> number generator. A short nonce protects transient keys and is an
>> 8-octet sequential number."
>>
>> http://rfc.zeromq.org/spec:26
>>
>> On Wed, Jul 2, 2014 at 9:13 PM, Diego Duclos
>> <diego.duclos at palmstonegames.com> wrote:
>> > Hello all,
>> >
>> > I've been reading up on the CurveZMQ and CurveCP specs.
>> > I've noticed they use a mix if 8 and 16 bytes nonces, who are then all
>> > passed to 24 bytes using a constant prefix.
>> > I was wondering when 8 byte and when 16 byte nonces are chosen as well
>> > as
>> > why.
>> >
>> > Kind Regards,
>> >
>> > Diego Duclos
>> > Palm Stone Games
>> >
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