PRESENTED BY
C.NEETHU
&
V.SONIA ESWARI

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QUANTUM CRYPTOGRAPHY-MAKING CODE UNBREAKABLE
ABSTRACT
 Major issue of secure communication
 Schemes published in recent times
o schemes limit the speed of communication
 Quantum cryptography-relies on cutting edge laws of physics
HISTORY
 Proposed by Stephen weisner ,1970
 “Conjugate coding”
 “BB84” –first quantum cryptography protocol
OVERVIEW
 Cryptography-”secret writing”
 Mathematical algebra for encryption and decryption
CLASSICAL CRYPTOGRAPHY
 Cryptography and crypto analysis
 Modern cryptographic techniques
o Public key-encryption
o Secret key- decryption
 central key distribution server
 Diffie hellman key exchange
BREAKING THE PUBLIC KEY
 c=me mod n
 Secret exponent
 Factorization algorithm
FUNDAMENTALS
 Polarization filter
 Photon
 “Entangled pairs”
POLARIZATION BY A FILTER
 Filter absorbs some light ,polarizes remainder
 Conjugate bases
 Characteristics behind quantum cryptography
APPLICATIONS
 Straightforward principle
 Orthogonal qubit state- Indistinguishable
 Solves the problem of key distribution
 Quantum key distribution
 Communication via quantum channel
STATE OF TECHNOLOGIES
 Two technologies
o Creating single photons
• Reducing the intensity of pulsed laser beam
o Detecting photons
• Avalanche photo diodes
CONCLUSION
Promises to revolutionize secure communication