Parasitic computing ppt

2. DefinitioN
Parasitic computing refers to the technique of using
the resources of one computer by another computer
without the knowledge of the former .
Distributed computing networks turn home users’
computers into part of a virtual super computer that
can perform time-intensive operations.

3. cont…
Parasitic computing uses computation power of
the computers connected to the internet in
solving complex mathematical problem.
Eg: Traveling salesman problem
satisfiability problem

4. theory
To solve problems
Generate large number of candidate solutions.
Send the solutions to destination node.
Test the candidates for their adequacy.
If result is true, the solution is valid.
else drop.
The result from each were used to build a
solution.

5. cont…
The mathematical problem is split into a
large number of simple logic problems.
They tag a logic problem onto check
sum.
Web server would process the request.
If the check sum is false, then server
would not respond to the request.
The whole result combine to form the
result of the mathematical problem.

6. cont…
The target nodes are answering logical
questions without knowing of doing so.
This does not violate the security of the
unknowing server.
Potential candidate protocol include
TCP,HTTP, or encryption/decryption with
secure socket layer.

7. how to trick other computer’s?
ALU
NIF
ALU
NIF
ALU
NIF

8. levels of communication
HTTP
TCP
IP
Network
HTTP
TCP
IP
Network
DROP
VALID
Parasite node Target web server

9. cont…
A single parasite node coordinates the
computations occurring remotely in the internet
protocols.
Each target node consist of
Arithmetic and Logic Unit (ALU)
Network InterFace (NIF)
A single home parasite initiates the computation,
sends messages to the targets directing them to
test and tabulates the result.

10. key Component
Checksum computation
Information sent across the internet is split it into
small chunks, or packets, that travel-often
independently of each other-to their destination.
Each packet bears a header that contains
Source address
Destination address
A numerical value related to the packet’s
content
When a computer receives a packet, it checks
for errors by performing a calculation and
comparing the result with the numerical value in
the packet’s header.

11. establishing a TCP connection

12. cont…
A connection is established with 3
messages,
The initiator sends a SYN to a remote
node.
If the remote node is willing to accept a
new connection, it responds with a
SYN/ACK message.
Finally, the initiator sends an ACK
message.

13. computing with TCP checksum
The message received by the target server
contains
an IP header
a TCP header
a candidate solution

15. cont…
Is a + b equal to c???
The checksum value in a TCP packet is
determined by c.
The data contains 16 bit words a and b.
If a + b! =c, then TCP rejects the
segment.
A message is valid only if a + b=c.

16. cont…
The targeted computers are various web servers
physically located in North America, Europe, and
Asia.
There is no negative acknowledgement.
The sender will keep a copy of the message.
In distributed system, it is not possible to
distinguish between a lost message and delayed
message. So a message is assumed to lost after
some time out period.

17. checksum computation
The sender breaks the message
consisting of N bits into 16 bit words.
The K words are added together using
binary arithmetic.
The sender then performs a bit-wise
complement on the checksum.
The sender incorporates the complement
of the checksum into the header of the
message.

18. cont…
The receiving computer again breaks the
received message into 16-bit segments and add
them together.
The checksum obtained by the receiver has to
be 1111111111111111.
If any bit along the message has been corrupted
during transmission, the checksum obtained by
the target will be different from all ones, in which
case target drops the message.

19. s1 s2 Sk
+
+
S1
S2
Sk
1110101011011011
0001010100100100
sump
sum
p
sum s1
p S2 sk
Create a new message of length N+16
SUM SUM
T p
= +S1+S2+…..+Sk
IF SUM =
1111111111111111
othrwise
Message correct
To HTTP
Message corrupt
drop
:
:
d
N bits
a
b
c

20. 2-SAT Problem

22. cont…
The 2-SAT problem involves 16 variables and
the operations AND and XOR.
In order to get a TRUE answer for P, each clause
shown in separate parentheses needs to be
independently TRUE.
To evaluate the vale of we generate a 32 bit
message M that contains all 16 variables, each
preceded by a zero.
TCP groups the bits in two 16 bit segments and
add them together.
The sum can have 4 outcomes.

23. cont…
If the clause has an XOR operator, is true
only when the checksum is (01).
If the clause has an AND operator, is true
only when the checksum is (10).
To turn a package into parasitic message
the parasitic node prepares a package,
preceded by a checksum, and continued
by a 32 bit sequence(S1,S2).

24. algorithm
S=create TCP segment
S. checksum = checksum
For each x
S. pad= pad with zeros (x)
send S
receive answer
if answer=true write x is a
solution

25. implementation
There are several ways to implement the
basic algorithm.
concurrency: Each concurrent
computation requires a separate a TCP
connection to http host.
connection reuse: Before a TCP
connection can be used, it must be
established. Once established TCP
segments can be sent to remote host.

26. how it differs from others?
In cluster computing, many computers
pool in their resources willingly.
Parasitic computing does not require the
willingness of any target machine.
In cluster computing, special softwares
are needed. Here not needed.

27. features
Parasitic computing theoretically offers the
chance to use the vast computational
power of the whole internet.
Several large computational problems can
be solved by engaging various web
servers physically located in different parts
of the world, each of which unknowingly
participated in the experiment.

28. cont…
Ethically challenging alternative for cluster
computing, as it uses resources without
consent of the computer’s owner
Parasitic computing does not compromise
the security of the targeted servers, and
access only those parts of the servers
that have been made explicitly available
for Internet Communication

29. problems
For parasites
Several computational cycles are taken
to process the possible solutions
Possibility of false negatives
Possibility of false positives

30. problems
For servers
Delays due to processing the
parasitic messages could cause a
denial of service
Almost impossible to prevent
someone from running a parasitic
job on your server

31. history
Parasitic computing was developed by the
scientist at the Notre Dame University,
Indiana(USA).
First Reported in journal ‘Nature’ in
2001 by Barabasi, Freech, Feong and
Brockman.

32. future
Enabling all the computers to swap
information and services they are needed
could lead to unparalleled emergent
behavior, drastically altering the current
use of the internet.

33. summary
Parasitic computing moves computation
onto what is logically the communication
infrastructure of the internet, blurring the
distinction between computing and
communication.
The current internet infrastructure permits
one computer to instruct other computer to
perform computational tasks that are
beyond the target’s immediate scope.