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GSIS / CIST Hwa Yean Lee 2005. 2. 21. Authenticated QKD protocol using one-time ID. Contents. Introduction Authentication with one-time ID Quantum Key distribution Security proof Conclusion. 1. Introduction. QKD (Quantum Key Distribution) protocols Advantage
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GSIS / CIST Hwa Yean Lee 2005. 2. 21 Authenticated QKD protocol using one-time ID
Contents • Introduction • Authentication with one-time ID • Quantum Key distribution • Security proof • Conclusion
1. Introduction • QKD (Quantum Key Distribution) protocols • Advantage : Unconditional security • Disadvantage : Vulnerability to the Man-in-the middle attack
1. Introduction(2) • Miloslav Dusek, Ondrej Haderka, Martin Hendrych, and Robert Myska, PRA, 60, 149-156 (1999) • Bao-Sen Shi, Jian Li, Jin-Ming Liu, Xiao-Feng Fan, Guang-Can Guo, Physics Letters A 281 83-87 (2001) • Guihua Zeng and Weiping Zhan, PRA, 61, 022303 (2000) • Daniel Ljunggren, Mohamed Bourennane, and Anders Karlsson, PRA, 62, 022305 (2000) • Takashi Mihara, PRA, 65, 052326 (2002)
2. Authentication with one-time ID • Preparation • Each user register him to the arbitrator : secret user and one-way function • One-way authentication key of a user, Alice is where is a count. • If is 1, then the Hadamard operator is applied, else the identity operator is applied to the ith qubit. • If does not have enough length to encode the qubits, then can be used, where .
2. Authentication with one-time ID (2) • Procedure of the authentication • Alice request a secure communication with Bob to the arbitrator. • The arbitrator prepares GHZ tripartite states. • He encodes Alice’s and Bob’s particles of GHZ states with and , respectively. where is Alice’s authentication key and is Bob’s.
2. Authentication with one-time ID (3) • Procedure of the authentication(2) • The arbitrator sends the encoded qubits to Alice and Bob respectively. • Alice and Bob decode their qubits with their authentication key and selects some bits. • Alice and Bob measure the bits and compare the results. • If the results are same, they can authenticate each other and do the following key distribution procedure. Otherwise they abort the protocol.
2. Authentication with one-time ID (4) • Transformation of the GHZ states
3. Quantum Key distribution • Procedure of the key distribution • Using the remaining particles after authentication, Alice and Bob randomly make an operation either or on each particles, respectively. • Alice sends her particles to the arbitrator and Bob sends his to Alice. • The arbitrator perform C-NOT operation, where the control qubit is his and the target qubits is from Alice. • The arbitrator measures each qubits(Alice’s and his) and announces the measurement outcomes are same(O) or not(X).
3. Quantum Key distribution (2) • Procedure of the key distribution (2) • Alice measures the GHZ particles received from Bob. • Using the information published by the arbitrator, Alice can find Bob’s sequence of the operations. • The Bob’s sequence of the operations can be used as a raw secret key.
The Arbitrator Alice Bob Eve 4. Security proof • Man-in-the middle attack • In the authentication process • Eve introduces errors with probability ¼ for each check bit in the authentication procedure. • On knowing the hash function, Eve can estimate only some bits of hashed value.
4. Security proof (2) • Intercept-resend attack • Intercepts both the qubits heading to Alice or Bob in the authentication and the qubits heading to Alice or the authentication in the key distribution. • When Eve intercepts one-side in the key distribution, the probability of detection is 3/8. • When Eve intercepts both-side in the key distribution, the probability of detection is 7/16. • But she cannot be aware of the exact key since Alice and Bob’s information of operations are not exposed to Eve.
4. Security proof (3) • Intercept-resend attack (2) • Intercept only the qubits transmitted in the key distribution • Eve only can know Alice and Bob use same operation or not. • The probability of inferring correct key is .
4. Security proof (4) • Eve Eavesdrops Alice’s (Bob’s) qubits transmitted to the arbitrator (Alice) after Alice and Bob make operations on decoded GHZ states
5. Conclusion • QKD with authentication using one-time ID is proposed. • Authentication with one-time ID can be used on the various fields of quantum cryptography. • The neutrality of the arbitrator is important for the security of the proposed scheme. More research on this problem are needed.