Quantum Encryption

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Quantum Encryption
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Conventional Private Key Encryption

• Substitution
• First known use was by Caesar to communicate to
  generals during war
• Improved by Vigeneres Cipher
• Very weak to frequency cryptanalysis

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• Transposition
• Rearranges the letters systematically but does
  not change their value
• Still weak to frequency and and common word
  attacks

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• One-time pad
• Similar to substitution
• Adds a randomly-generated key to the message
• Absolutely secure because the key is longer than
  the message and used only once

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Overview of Conventional Encryption

• Secure for private use, but requires secure
  transmission of private key
• A variation on private key encryption, public key
  encryption, provides a workaround for key
  transmission on the internet, but if intercepted
  is not 100 secure

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Quantum CryptographyPoints of Interest

• Provides 100 secure transmission of a private
  key of unlimited length
• Requires uninterrupted photon stream for
  transmission
• The original message is encoded and sent via
  quantum polarities of the light

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Fiber Optic Cable

• For communications, many hair-thin pieces are
  used because they transmit better than one thick
  piece
• For normal data transmission pulses of light are
  used, and travel much better than the quantum
  polarities used for quantum transmission

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Usual Process of Fiber Optic Communication

• Pulses of light are sent through fiber optics to
  relay huts

Quantum Cryptography

• Message is encrypted and sent in quantum
  polarities of the light

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Polarization

• Describes the vibrational direction of the
  electric field associated with the light

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Continuous Photon Stream

• Requires unbroken length of fiberoptic cable
• Sensitive to any interception, due to uncertainty
  principle

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The FTIR Fourier Transform Infrared spectrometer
Advantages
Limiting Factors

• Transmits the full IR spectrum
• Analyzes the full spectrum simultaneously
• Automatically graphs data

• Beam splitter
• Range of motion of mirrors
• Light source and detector

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FTIR and Fiber OpticsWhat we did

• Acquired FTIR drivers license
• Acquired fiber optic cable
• Set up consisted of a ring stand suspending the
  fiber optic cable in line with FTIR source and
  detector
• Ran a series of scans on one sample of fiber
  optic cable

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Results
Transmittance
Wave number