Wednesday, October 26, 2005

Interesting Graphical Explanation

Quantum Cryptography
  1. Alice needs to generate an encryption key to send Bob a secure e-mail
  2. Her photon generator spits out photons of light, each with a random polarization—horizontal, vertical, or diagonal in one of two directions—representing the key
  3. Alice's and Bob's systems agree on the value of each polarization—either a 1 or a 0
  4. Bob receives the secure e-mail and measures the key's polarizations, changing some of them in the process
  5. Bob sends the results to Alice, whose device tells Bob's system which photons were measured correctly. The others are thrown out
  6. Bob figures out the encryption key and decrypts the e-mail
  7. If Eve tries to eavesdrop, she changes the polarizations of some of the photons but isn't sure which ones she's changed.



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