"CONTENTS ? Introduction ? Definition ? Internet communication ? Proof-of-concept ? Working of parasitic computing ? Implementation ofTCP checksum ? 2-sat problem ? Issues ? Advantages ? Disadvantages ? Conclusion? ReferencesIntroduction ? First reported in Journal “Nature” in 2001 by Barabasi ? A form of distributed computing. ? Used for solving complex computational problems. ? Exploits standard set of communication protocol on internet. ? It is not cracking. ? Mainly used to solve np-complete problems that are satisfiability problem.Definition ? A "parasite" computer attempts to solve a complex task by breaking it up into many small components. ? the processing of these components are distributed to remote computers which perform this processing without the knowledge or consent of those owning the remote computing resources. ? This is achieved through the use of theTCP/IP Internet protocol.Internet Communication When user selects a URL ? Actions at sender ? Open a TCP connection to a web server ? Issue a HTTP request over TCP connection ? TCP message is carried via IP ? Actions at receiver ? Receive message through IP ? Validate checksum at TCP ? Validated pushed to HTTP ? Not validated discard the packetProof-of-concept ? Solved the SAT problem. ? NP-Complete. ? Usually solved by testing several candidate solutions. ? Each candidate solution can be examined in parallel.Working / architectureimplementation of TCP checksum2-sat problem Co n ti n u e d …Solving 2-sat problem using tcpchecksum ? Sender breaks message into 16 bit words. ? These words are added together. ? The result is inverted and sent with message. ? Receiver breaks message into 16 bit words. ? All words are added together. ? If the result is all ones, the message is valid. ? Otherwise, the message is dropped. Co n ti n u e d …….."