lecture_20

lecture_20 - MIT 6.443J / 8.371J / 18.409 / MAS.865 Quantum...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: MIT 6.443J / 8.371J / 18.409 / MAS.865 Quantum Information Science April 27, 2006 Unconditional Security of QKD 1. Cryptography 2. Quantum Key Distribution: BB84 3. EPR Protocol 4. CSS Code Protocol 5. Secure BB84 1 Crytography secret comm. PKC auth DSS In the Vernam Cipher (one-time pad), Alice and Bob share a secret key k . A key k B msg m m' m'+k=m m+k Eve has m + k , but I ( m + k, m ) = H ( m + k ) H ( m + k/m ) = H ( m + k ) H ( k ) = 0 The key k is called a pad. It is referred to as one-time because k cant be reused. 1 Distribution of k security criterion I (Eve , key) = 2 l where resources required poly( l ). 2 Quantum Key Distribution: BB84 A rand b in {0,1} rand b' in {0,1} a' Bob H H channel a = , | | 1 = , Keep all bits for which b = b . A and B hash obtain key k . Thm. Info gain disturbance. In any attempt to distinguish non-orthogonal states and | , information gain is only possible at the expense of disturbing the states. | Proof. WLOG assume | | u | | v | | u...
View Full Document

This note was uploaded on 02/07/2012 for the course MAS 6.443J taught by Professor Petershor during the Spring '06 term at MIT.

Page1 / 7

lecture_20 - MIT 6.443J / 8.371J / 18.409 / MAS.865 Quantum...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online