p2psp team mailing list archive

[Cristóbal Medina López <cristobalmedinalopez@xxxxxxxxx>]

Hi,

It's clear now :)

Thanks!

El mar., 31 de marzo de 2015 a las 16:22, Vicente Gonzalez (<
vicente.gonzalez.ruiz@xxxxxxxxx>) escribió:

> Thanks!
>
> On Tue, Mar 31, 2015 at 2:17 PM Ilshat Shakirov <im.shakirov@xxxxxxxxx>
> wrote:
>
>> ok, n = 4.
>> Formula is for exactly 2 trusted peer. It shows the number of
>> permutations of 2 trusted peers in node's peer list.
>> So the size of peer list is n - 1 = 3;
>> So the permutations will be
>> p, T, T
>> T, p, T
>> T, T, p
>>
>>
>> 2015-03-31 16:46 GMT+05:00 Cristóbal Medina López <
>> cristobalmedinalopez@xxxxxxxxx>:
>>
>>> Hi,
>>>
>>> Yes, I mean the first one (N = (n - 1) * (n - 2) / 2 ). I still don't
>>> get why N is the number of possible permutations in the attacker's peer
>>> list. For a simple example where the team size is 4 (n=4). Could you write
>>> down the 3 possible permutations?
>>>
>>> Thank you very much,
>>> You're doing a great work.
>>>
>>> Regards.
>>>
>>> PS: We prefer work with pull requests on github ;)
>>>
>>> El mar., 31 de marzo de 2015 a las 12:10, Ilshat Shakirov (<
>>> im.shakirov@xxxxxxxxx>) escribió:
>>>
>>>> Could you explain at length the previous formula? (anyway we think that
>>>>> it also works perfectly)
>>>>
>>>> Sorry, I didn't understand your question. Do you mean
>>>>
>>>>> *N = (n - 1) * (n - 2) / 2*
>>>>>
>>>> or
>>>>
>>>>> http://p2psp.org/en/p2psp-protocol?cap=indexsu11.xht#x20-160004.11
>>>>>
>>>>  ?
>>>>
>>>> If you mean *N = (n - 1) * (n - 2) / 2* so it's a simply combination
>>>> (n-1, 2).
>>>> Btw, n is size of the team without splitter.
>>>>
>>>> 2015-03-31 14:33 GMT+05:00 Cristóbal Medina López <
>>>> cristobalmedinalopez@xxxxxxxxx>:
>>>>
>>>>> Hi Ilshat,
>>>>>
>>>>> We think that the formula is fine. Only one question (see bellow):
>>>>>
>>>>> El lun., 30 de marzo de 2015 a las 14:58, Ilshat Shakirov (<
>>>>> im.shakirov@xxxxxxxxx>) escribió:
>>>>>
>>>>>> Hello!,
>>>>>>
>>>>>> I got a new results from experiments with new parameters (2 trusted
>>>>>> and one attacker), and it doesn't match with expected results from
>>>>>> http://p2psp.org/en/p2psp-protocol?cap=indexsu11.xht#x20-160004.11
>>>>>> (formula 11)
>>>>>> But I deduced new formula (only for these params for now (T=2, A=1)):
>>>>>>
>>>>>> ​
>>>>>> , where n is team size.
>>>>>> ​Let me explain it:
>>>>>> It just a formula for expected value for discrete random variable. So
>>>>>> let describe our discrete variable:
>>>>>> We have n peers, 2 trusted peers and one attacker. Size of each
>>>>>> node's peer list is* n - 1*. Number of possible permutations for 2
>>>>>> trusted peers in attacker's peer list is *N = (n - 1) * (n - 2) / 2.*
>>>>>>
>>>>>
>>>>> Could you explain at length the previous formula? (anyway we think
>>>>> that it also works perfectly)
>>>>>
>>>>>
>>>>>>
>>>>>> The probability for getting only one poisoned chunk in the netowrk is *P(1)
>>>>>> = (n - 2) / N*; (because we're getting only one poisoned chunk when
>>>>>> trusted peer is the first in attacker's peer list, so there is n-2 variants
>>>>>> of this situation).
>>>>>> Next, *P(2) = (n - 3) / N*, P(x) =* (n - x - 1) / N*
>>>>>> The max possible number of poisoned chunks in network with 2 trusted
>>>>>> peer and one attacker is n - 2 (n - attacker - trusted);
>>>>>> So, we must only to compute expected value as sum of *P(x)*x*.
>>>>>>
>>>>>> Formula can be easily generalized to different numbers of attackers
>>>>>> and trusted peers, but first I want to know your opinion about it.
>>>>>> What do you think? =)
>>>>>> <https://en.wikipedia.org/wiki/Discrete_random_variable>
>>>>>>
>>>>>>
>>>>> Please, check that the following python code implements your formula:
>>>>>
>>>>> x = 0.0
>>>>> n = 10
>>>>> for i in range(1,n-2):
>>>>>     y=2.0*i*(n-i-1)/((n-1)*(n-2))
>>>>>     print y, i
>>>>>     x+=y
>>>>> print x
>>>>>
>>>>> Thanks,
>>>>> Regards.
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>> 2015-03-29 1:43 GMT+05:00 Ilshat Shakirov <im.shakirov@xxxxxxxxx>:
>>>>>>
>>>>>>> Hello!,
>>>>>>>
>>>>>>> Sorry for the delay in the response.
>>>>>>> I have just improved the Peersim impl of P2PSP:
>>>>>>> - malicious peer connects to the team after some delay (magic
>>>>>>> constant :))
>>>>>>> - *CHUNK *message have 4 times more delay than other messages
>>>>>>> (hello, goodbye, etc.)
>>>>>>> - trusted and malicious peers are chosen randomly at the begin of
>>>>>>> simulation
>>>>>>>
>>>>>>> I have performed new experiments with these improvements, it can be
>>>>>>> accessed at the same doc - https://docs.google.com/spreadsheets/d/
>>>>>>> 1pc6yb87xJy8gNkWSWvvCvjAjR6WBFdOzCbPvO-zEooU/edit#gid=0 - it has 2
>>>>>>> new tabs - raw2 and result2.
>>>>>>> *raw2 *tab have 2 sets of data - the first one was performed
>>>>>>> without different latencies, and the second one was performed with
>>>>>>> different latencies.
>>>>>>> Could you please evaluate results? What the next steps you want to
>>>>>>> see with peersim impl of p2psp? =) I want to perform experiments with
>>>>>>> different numbers of trusted peers and attackers, in order to confirm
>>>>>>> theroretical analysis given in paper.
>>>>>>>
>>>>>>> Also, I want to store all the logs from each experiment in the same
>>>>>>> place. I want to use dropbox for this (shared dir). What do you think? =)
>>>>>>>
>>>>>>> Currently, Im preparing scripts (bash and bat) to run simulation, so
>>>>>>> there will be possible to perform experiments without setting up IDE.
>>>>>>>
>>>>>>> ps Could you please include me to sim project on github? Or we will
>>>>>>> work with pull requests? =)
>>>>>>>
>>>>>>> Thanks in advance!
>>>>>>>
>>>>>>>
>>>>>>> 2015-03-20 18:48 GMT+06:00 Vicente Gonzalez <
>>>>>>> vicente.gonzalez.ruiz@xxxxxxxxx>:
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> 2015-03-20 9:59 GMT+01:00 Ilshat Shakirov <im.shakirov@xxxxxxxxx>:
>>>>>>>>
>>>>>>>> I don't know the procedure you are using to add peers to a team
>>>>>>>>>> (how the peers contact the splitter, receives the list of peers of the
>>>>>>>>>> splitter and send the [hello] message to the peers that are in the list),
>>>>>>>>>> but I suppose that this procedure is similar to one used in a real team.
>>>>>>>>>
>>>>>>>>> Yes, the peers are added to team as it described in DBS of rules
>>>>>>>>> (new peer sends HELLO to splitter, splitter sends list of peers, peer sends
>>>>>>>>> HELLO to rest of team).
>>>>>>>>>
>>>>>>>>
>>>>>>>> OK.
>>>>>>>>
>>>>>>>>
>>>>>>>>> I have new hypothesis - how much time is spent for sending
>>>>>>>>> chunks? and for sending simple messages, like HELLO/GOODBYE. In peersim
>>>>>>>>> implementation there is no difference in times between these two types of
>>>>>>>>> message. If it's able to send 2 or more simple messages while one chunk is
>>>>>>>>> sending, then simulation results will match with expected results.
>>>>>>>>>
>>>>>>>>
>>>>>>>> When a peer is introducing himself to the rest of the team only
>>>>>>>> sends [hello]s. To interlace [hello]s and chunks, the splitter should send
>>>>>>>> first to it a chunk, and this is done after receiving the list of peers
>>>>>>>> from the splitter. This does not happen.
>>>>>>>>
>>>>>>>> In my opinion, a better result (not only for this experiment) could
>>>>>>>> be obtained if you assign a latency to each message that depends on the
>>>>>>>> message's length.
>>>>>>>>
>>>>>>>>
>>>>>>>>> This means that if the peer 34 were the trusted peer, the attacker
>>>>>>>>>> would send only one poisoned chunk before it is reported. For this reason,
>>>>>>>>>> I think that the order of the peers in the lists should have some influence
>>>>>>>>>> in the average number of poisoned chunks.
>>>>>>>>>
>>>>>>>>> There is such results already. I.e. cell D43 in google sheet
>>>>>>>>> <https://docs.google.com/spreadsheets/d/1pc6yb87xJy8gNkWSWvvCvjAjR6WBFdOzCbPvO-zEooU/edit#gid=0>.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> I see :-)
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Also, I can remove the latency for simple messages (like hello and
>>>>>>>>> goodbye), and (I suppose) results will match with expected results.
>>>>>>>>>
>>>>>>>>
>>>>>>>> No. Please, consider first my idea (longer messages will take more
>>>>>>>> time traveling that shorter ones).  And, randomize, if possible, the order
>>>>>>>> (or time) in which peers join the team.
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> An accurate P2PSP simulator is very interesting for researching
>>>>>>>>>> the performance of the P2PSP. Any kind of advance/facility in this
>>>>>>>>>> direction is really appreciated :-)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>> Ok, I will begin to write readme file about performing experiments
>>>>>>>>> =)
>>>>>>>>>
>>>>>>>>
>>>>>>>> Again, thanks. Your work will be very helpful!!
>>>>>>>>
>>>>>>>> Best,
>>>>>>>> Vi.
>>>>>>>>
>>>>>>>> --
>>>>>>>> Vicente González Ruiz
>>>>>>>> Depto de Informática
>>>>>>>> Escuela Técnica Superior de Ingeniería
>>>>>>>> Universidad de Almería
>>>>>>>>
>>>>>>>> Carretera Sacramento S/N
>>>>>>>> 04120, La Cañada de San Urbano
>>>>>>>> Almería, España
>>>>>>>>
>>>>>>>> e-mail: vruiz@xxxxxx
>>>>>>>> http://www.ual.es/~vruiz
>>>>>>>> tel: +34 950 015711
>>>>>>>> fax: +34 950 015486
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>
>>