Re: [ppsp] questions about merkle hash tree mechanism for integrity protection of content between peers

[Dusan Gabrijelcic <[e-mail]>]

Hi Deng,

On Tue, Nov 6, 2012 at 8:17 AM, Arno Bakker <[e-mail]> wrote:

> On 05/11/2012 18:41, 邓灵莉/Lingli Deng wrote:
>
>> Hi Arno,
>>
>> Thank you for the impressive speech and demos this morning.
>>
>>
>  2)For ECS proposal, I doubt the one-to-one encryption negotiation is
>> scalable for a peer serving more than one peers at a time. Since you are
>> not targeting DRM requirements, revocable group keys may suite your
>> needs, while the data can be encrypted once and for all given the group
>> membership remains unchanged.
>>
>>
> Dusan?
>

I hope I had understood your questions correctly. According to our tests
and evaluations the ECS cryptographic handshake using plain digital
signature (one-to-one encryption negotiation) should scale reasonably well
for expected peers load (number of peers in swam(s), in connection,
regarding churn and taking in account normal peer settings). Ordinary host
should easily handle few hundreds of ECS handshakes per second (measured
through OpenSSL) which should be sufficient even for large number of
concurrently open connections and, lets say, 1% churn per second.

The group key and encrypting the content (not exchanged data in connection
since it is not always the same) once for all would really decrease the
load on peer but it is regarded as highly insecure, except in very
restricted settings. As you mention static group membership, the ECS
protocol doesn't assume any limitations on group membership; peers can join
and leave at will (but according the credentials they posses). And, the
protocol provides in application data communication protection other
security services besides confidentially (encryption) as well. Nowadays
they are standard in most network protocols, for example in IPSec or
TLS/DTLS.

Things can get harsher on heavily loaded ingest points, but here a swarm
initiator has other mechanisms that can be used to mitigate the load, like
auxiliary peers, cryptographic accelerators (quite common in VPN/SSL
settings), cloud seeding, etc.

Hope this answers your questions.

Kind regards, Dusan.
-- 
~~~~~~~~~~
Dusan Gabrijelcic
e-mail: [e-mail]