Re: [IPsec] Questions about RFC 5723

[Yaron Sheffer <[e-mail]>]

Paul, please don't hesitate to submit an editorial erratum if you think 
one is needed. If you don't "get" this RFC, it probably means something 
is missing.

Thanks,
	Yaron

On 12/07/2019 17:34, Paul Wouters wrote:
> On Fri, 12 Jul 2019, Valery Smyslov wrote:
> 
>> A single (pair of ) IPsec SA is created as result of IKE_AUTH following
>> IKE_SA_RESUME, as if it follows IKE_SA_INIT instead of IKE_SA_RESUME.
>> If more IPsec SAs are needed they are created via CREATE_CHILD_SA,
>> as usual.
> 
> Ahhhhh I totally missed this part when reading the document. Things make
> a lot more sense now. Thanks!
> 
>>> Also, when using PFS, these CREATE_CHILD_SA's would do a DH again, at
>>> which point one wonders why to do resumption at all if you have more
>>> than one IPsec SA, as you would be doing DH's anyway for all children,
>>> you might as well do one more for a regular IKE_SA_INIT ?
>>
>> In any case you save on authentication (this may involve signature
>> computing/verification and probably human intervention in case of EAP).
> 
> Indeed. Thanks for the clarifications!
> 
> I guess formally, we would need to add the previous IKE traffic counters
> to the current one, since these are all derived from the same DH.
> 
> (yes, for FIPS we need to ensure there is not more than 2^20 or so AES
> packets of IKE traffic, even though reaching that would be quite the
> accomplishment)
> 
> Paul