Principles of Quantum Cryptography
The principles of Quantum Cryptography, a science dedicated to hiding, or keeping secret, the content of a message from third parties, are studied.
Abstract
Principles of Quantum Cryptography 1 Sebastien Tanzilli, sebastien.tanzilli@inphyni.cnrs.fr Team “Quantum Photonics & Information” UMR 7010 http://inphyni.cnrs.fr Journee Science et Progres de la F2S Les technologies quantiques : en route vers les applications jeudi 11 janvier 2018, ENS Paris Outline 2 1. Definition, wording, and some historical examples 2. Basics of classical cipher methods, RSA & one-time-pad 3. Incompatible quantum basis 4. The Bennett & Brassard (BB84) protocol with single photons 5. Basic eavesdropping strategies 6. Conclusion 1.1 Definition of Cryptography • Science dedicated to hiding, or keeping secret, the content of a message from third parties 3 • When did cryptography start ? very ancient times • Today ? an entire societal issue ‣ Need for secure links everywhere • Internet (e-mails, private navigation, paiements, etc.) • Wired and unwired Com (calls, SMS, MMS, etc.) • Cash withdrawers (credit card) • ... • Encryption / Decryption ➜ Cipher / Decipher ‣ Ciphertext / Plaintext (clear) 4 1.1 Wording related to Cryptography • The usual suspects • The friend parties :Alice & Bob • The Adversary : Eve (Eavesdropper) ‣ Unl