19-06-2012, 02:33 PM
Quantum Cryptography
Quantum Cryptography.ppt (Size: 405.5 KB / Downloads: 38)
what is Quantum Mechanics?
Quantum Mechanics is the study of mechanical systems whose dimensions are close to the atomic scale.
Quantum effects, such as stable electron orbits, entaglement etc.. are not observable on a macroscopic scale, and exist only at the microscopic level.
Applications of Quantum Mechanics range from explaining features of the subatomic world to computational chemistry.
Current research is being done in the fields of Quantum Cryptography, Quantum Computing, and Quantum Teleportation.
Finding Eve
Problem
If an eavesdropper were to gain information about the photons' polarization, the laws of quantum physics dictates that the quantum state of the photons would be altered, thus causing errors in Bob's measurements.
Solution
Alice and Bob compare a subset of remaining bit strings. If more than p bits differ, the key distribution process is aborted and repeated.
Privacy Amplification
As it is impossible to distinguish between eavesdropping and transmission imperfections, a threshhold p (currently 20%) is set for error margins.
If differences occur above the threshhold, privacy amplification can occur.
A new key is created by using Alice and Bob's key to produce a new, shorter key, in such a way that the eavesdropper's knowledge about the new key is negligible.
Quantum Cryptography.ppt (Size: 405.5 KB / Downloads: 38)
what is Quantum Mechanics?
Quantum Mechanics is the study of mechanical systems whose dimensions are close to the atomic scale.
Quantum effects, such as stable electron orbits, entaglement etc.. are not observable on a macroscopic scale, and exist only at the microscopic level.
Applications of Quantum Mechanics range from explaining features of the subatomic world to computational chemistry.
Current research is being done in the fields of Quantum Cryptography, Quantum Computing, and Quantum Teleportation.
Finding Eve
Problem
If an eavesdropper were to gain information about the photons' polarization, the laws of quantum physics dictates that the quantum state of the photons would be altered, thus causing errors in Bob's measurements.
Solution
Alice and Bob compare a subset of remaining bit strings. If more than p bits differ, the key distribution process is aborted and repeated.
Privacy Amplification
As it is impossible to distinguish between eavesdropping and transmission imperfections, a threshhold p (currently 20%) is set for error margins.
If differences occur above the threshhold, privacy amplification can occur.
A new key is created by using Alice and Bob's key to produce a new, shorter key, in such a way that the eavesdropper's knowledge about the new key is negligible.