Download presentation

1
**Quantum Cryptography Post Tenebras Lux!**

Grégoire Ribordy Changer Logo A Quantum Leap for Cryptography Logo en bas ?

2
**Outline Introduction: Cryptography Quantum Information Processing**

Quantum cryptography protocole Practical system Applications and outlook

3
**Cryptography Eve Bob Alice Key transmission**

Document Document Secure communication Bob Key Key Decryption Encryption Alice Key transmission Logo en bas: sans slogan; slogan à droite Key generation

4
**Secret key cryptography**

Encryption and decryption key identical Problem: Key exchange The longer the key, the higher the security One-time pad

5
**Public key cryptography**

Encryption key Decryption key (public) (private) One way function Key distribution problem solved? Caution: vulnerable Mathematical progress: Security is based on mathematical assumptions Technological progress: Computers become more powerful 13 31 = 403

6
**Computational complexity**

Complexity of a computer program… P(n) = n + n2 + n3+…+nk E(n) = exp (n) = n + n2 + n3 + n4 … + n In cryptography

7
**Another look at Moore’s Law**

Trend of computer chip development hit a « quantum wall » Potential of quantum physics not yet exploited in industrial applications

8
**Quantum Physics and Cryptography**

Public key cryptography cracking Eve Document Document Secure communication Bob Key Key Decryption Encryption Alice Key transmission Logo en bas: sans slogan; slogan à droite Key generation

9
**Quantum Random Number Generator**

Physical randomness source Commercially available Applications Cryptography Numerical simulations Statistics Concurrence: logiciel QRNG (actuellement – 2e gén – application: SSL – contact avec fabriquant cartes crypto)

10
**Quantum Physics and Cryptography**

Public key cryptography cracking Eve Document Document Secure communication Bob Key Key Decryption Encryption Alice Key transmission Logo en bas: sans slogan; slogan à droite Key generation

11
**Classical vs quantum communications**

Communication System Secure channel over dedicated optical fiber Absolute security guaranteed by the laws of quantum physics "0" "1" Fragile ! Mentionner Heisenberg Limitation de la distance

12
**Quantum communications**

Transmitting information with a single-photon Light Polarization Linear States = "0" = "1"

13
Eavesdropping (1) A single-photon constitutes an elementary quantum system It cannot be split Semi-transparent mirror 50%

14
**Eavesdropping (2) Communication interception**

Use quantum physics to force spy to introduce errors in the communication Alice Bob "0" "0" Eve

15
**Polarization measurement**

Using polarizing filters to measure polarization states and and probabilistic modification But and ? Heisenberg’s Uncertainty Relations = "0" = "0" Base 1 Base 2 = "1" = "1"

16
**Quantum Cryptography Protocole**

BB84 A better name: Quantum Key Distribution

17
**Key Distillation (ideal case)**

Transmission Qubits Alice Bob Quantum channel Sifted key Reconciliation Basis QBER estimate 0 : no eavesdropping Reveals rather than prevents eavesdropping A better name: quantum key distribution QBER = > 0 : eavesdropping

18
**Key Distillation (realistic case)**

Transmission Qubits Alice Bob Quantum channel (losses) Raw key Public channel Reconciliation Basis Sifted key QBER estimate correction Error amplification Privacy Key Key

19
**Implementing the quantum channel**

Necessary components Channel Single-Photon Source Single-Photon Detector

20
**Quantum Cryptography System**

Collaboration: id Quantique – UniGe Pilot tests in 2003

21
Field tests Optical fibers Distance: 67 km Genève – Lausanne

22
**Deployment Computer network A Computer network B Optical Fiber**

(classical channel) Optical Fiber (quantum channel) QKD Hardware QKD Hardware Traffic Network A to B Encrypted traffic Encryption Main features Encryption Transparent High-bit rate (1 Gbit/s) Remote monitoring Automated key management Classical channel Decryption Encrypted traffic Traffic Network B to A Quantum channel Key exchange

23
**Applications Advantages Constraints**

Automated key management Long term security Constraints Optical fiber Distance < 100 km High-security applications in a metropolitan area network Financial sector, e-government Storage, disaster recovery

24
**Extending the distance**

Secure relays Improved components Photon counting detectors Photonic crystal fibers: 0.2 dB/km 0.02 dB/km Quantum repeater Free-space links to satellites

25
**Quantum Repeater Quantum Teleportation Rudimentary quantum repeater**

Quantum version of a fax Recently at Unige: teleportation of a photon over 2km Rudimentary quantum repeater

26
**Free-space QKD Satellites = secure relay**

Experiments over horizontal links 23.4 km in the German Alps Tokyo Genève

27
Post Tenebras Lux?

28
**Thank you for your attention**

id Quantique SA Chemin de la Marbrerie, 3 CH-1227 Carouge / Geneva Switzerland Ph: Fax:

Similar presentations

OK

Implementation of Practically Secure Quantum Bit Commitment Protocol Ariel Danan School of Physics Tel Aviv University September 2008.

Implementation of Practically Secure Quantum Bit Commitment Protocol Ariel Danan School of Physics Tel Aviv University September 2008.

© 2019 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google