An Introduction to Quantum Computers and Quantum Cryptography Computer Network Security Prepared by: Nima Bayan, P.Eng. Fall 2003
Contents ! Introduction " Cryptography and Relativity " Quantum Algorithms " Quantum Computers ! State of the art ! Applications ! Impact on cryptography ! Future of cryptography ! Suggested references Quantum Computers Presentation, NB 2
Introduction: Cryptography and Relativity ! Cryptography helps when there are uncertain transmission conditions (Passive and active attacks on the network) " Receiver problem (eavesdropping) " Sender problem (masquerading) " Authenticity problem (Replay, Delay) " Traffic analysis ! Relativity Helps: A key part of Einstein’s special theory of relativity " It is impossible to send signals faster than speed of light " Use this to open two concurrent sessions for Alice and Bob Quantum Computers Presentation, NB 3
Introduction: Quantum Algorithms vs. Classical Algorithms ! Classical Computers ! Quantum computers " Alan Turing (1936) " David Deutsch (1985) ! Classical computation ! Quant. computation " Based on bits (0 or 1) " Based on qubits (0,1 and/or 0&1 !!!) ! Classical factoring ! Quant. factoring " Hard problems (NP) " Peter Shor (1994) ! Classical search ! Quant. Search " Bubble method (N/2) " Amazing speed ( √ N) " Lov Grover Quantum Computers Presentation, NB 4
Quantum Computers ! Make use of two basic rules of quantum physics " Superposition " Entanglement Quantum Computers Presentation, NB 5
Quantum Computers Presentation, NB 6
State of the art ! Quantum computers are built on the basis of any quantic element " Atom based QC (IBM 7 qubit computer) " Electron based QC (U of Cambridge, UK) " Photon based QCs Quantum Computers Presentation, NB 7
State of the art ! IBM 7 qubit computer ! Dr. Chuang ! Fluorocarbon based ! Sequence of radio pulses ! The atoms will change into superposition state Quantum Computers Presentation, NB 8
State of the art ! Quantum Gyroscopes " Jonathan Dowling (NASA) ! Other applications ! Programming, ... " Edward Farhi (MIT) Quantum Computers Presentation, NB 9
Impact on cryptography ! Disadvantages ! Advantages " All current hard problems " No intermediate (RSA, ...) are not going to calculations remain hard " New quantum based (more " Using Shor’s method bits more complex) algorithms " Parallel sessions for Alice and Bob " Faster search routines " Faster factorizing algorithms Quantum Computers Presentation, NB 10
Suggested references ! General: " http://www.qubit.org/ " http://www.cs.caltech.edu/~westside/quantum-intro.html " http://www.qubyte.com/ " http://computer.howstuffworks.com/quantum-computer.htm " http://physicsweb.org/article/world/15/4/4/1 ! Programming languages for quantum computers " http://tph.tuwien.ac.at/~oemer/qcl.html ! Quantum computers and cryptography " http://en2.wikipedia.org/wiki/Quantum_computer " http://unisci.com/stories/20021/0215026.htm " http://www.qmechanics.supanet.com ! MIT’s Technology Review (March 2003) ! Spectrum (2002) Quantum Computers Presentation, NB 11
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