بررسي پروتكل BB84 و ارائه گونه اي اصلاح يافته از آن مبتني بردرهم تنيدگي كوانتومي

چكيده انگليسي :

Analyzing BB84 Protocol and Proposing a Modified Entanglement Based Version Amir Bakhshandeh a bakhshandeh@ec iut ac ir May 1 2016 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Prof Mohammad Dakhil AlianAbstract Abstract Through the ages the security of information has always been a major concern Mankind has used simple butinteresting and sometimes artistic procedures in order to hide its information from eavesdroppers With the advances in thefield of information theory and cryptography a new approach was taken Cryptography transitioned from an art form to asolid math based science and modern cryptography was born Since the emergence of modern cryptography symmetric keyalgorithms have been the main providers of information security The main difficulty in using such algorithms is the problemof key sharing Public key algorithms provide us with methods to share a key with a party via an insecure channel Thesecurity of these algorithms is based on their computational complexity The development of quantum information sciencehas gravely endangered the security of public key algorithms For instance Shor algorithm has the ability to decrypt theRSA public key cryptosystem on a quantum computer in polynomial time Employing quantum cryptography was thenext logical step Quantum cryptography guarantees the security of information by physical laws of quantum mechanics BB84 was the first quantum key distribution protocol This protocol offers the parties a method to securely share a keyusing quantum states in an insecure environment and in the presence of malicious parties Eavesdropping will introducedisturbance in the process which can easily be detected by the legitimate parties In this dissertation we propose a modifiedversion of the BB84 protocol In this protocol sender uses a group of quantum states and applies a non local transformationto them and then starts sending them to the receiver one by one The parties use an authenticated classical side channel soafter each transmission the receiver informs the sender of the arrival of the qubit After receiving all the states the receiverperforms a measurement and the parties arrive at a conclusion In this protocol the attacker only has access to one qubit at atime So he can t undo the non local transformation We calculate the maximum mutual information that the eavesdroppergains on the shared secret key using an intercept resend attack and the quantum bit error rate introduced by the attacker as aconsequence of this attack We also show that for a fixed amount of error the attacker s maximum information on the keyis significantly less than the original BB84 protocol Key Words Quantum Cryptography Quantum Key Distribution

بخشنده، امير

بررسي پروتكل BB84 و ارائه گونه اي اصلاح يافته از آن مبتني بردرهم تنيدگي كوانتومي

رمزنگاري كوانتومي , تبادل كليد كوانتومي