p2psp team mailing list archive

[Vicente Gonzalez <vicente.gonzalez.ruiz@xxxxxxxxx>]

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
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>
>