April 24, 2016 Modern Physics- Nicholas Chao 1
April 24, 2016 Modern Physics- Nicholas Chao 1
Presentation Outline
� What is Cryptography?
� Keys
� Quantum Cryptography
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What is Cryptography?
� “The art of writing or solving codes” � History
� Classical Cryptography � World War II � Modern Cryptography
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History: Classical Cryptography
� Pen and Paper � Simple Mechanical Aids
� The Jefferson Cylinder � Encrypt and Decrypt Mechanism
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History: World War II
� Enigma Rotor Machine � Alan Turing � The Imitation Game
� Cryptanalysis � Breaking of Codes and Ciphers
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History: Modern Cryptography
� Keys to Encrypt and Decrypt Information � DES: Data Encryption Standard � AES: Advanced Encryption Standard � (a) Triple DES Encryption � (b) Decryption
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Keys
� Modern keys are based on mathematics � Keys are strings of bits � Bits
� 0 or 1 � The more bits, the more possible
combinations � How many possible keys are there for
an 8-bit key?
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How keys work
� Algorithm is public knowledge, however, you need a key to get the correct answer.
� Analogy: Lock and key
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Public Keys
� Kerckhoff's Principle: All algorithms must be public; only the keys are secret
� How can a key be public? � Public and private keys
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Symmetric vs. Asymmetric
� Symmetric key Algorithm � All parties must have the same key
� Asymmetric key Algorithm � Each party has a ○ Public Key ○ Private Key
� Mathematically linked
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Symmetric Key Example
� Bob and Alice � Security Issues
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Asymmetric Key Example
� Bob and Alice � Computationally
intensive
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Quantum Cryptography
� Cryptography using physics � Keys are based on physics, not math
� Quantum Key Distribution � BB84
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Random Numbers
� Generated based on QM physical randomness � Atomic/Subatomic level ○ Gas molecules bouncing off each other
� Thermal Noise � Outcome of QM cannot in principle be
predicted � This is the gold standard of randomness
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Quantum Cryptography BB84
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Quantum Cryptography Example
� What about Trudy?
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Post-Quantum Cryptography
� Quantum Resistance Algorithms � Secure Against Quantum Computers! � Relies on physical properties rather than
mathematics
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Conclusion
� History of Cryptography � Symmetric and Asymmetric Keys � Quantum Cryptography
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Sources (Page 1) � Bennett, Charles H., Tai Mor, and John
A. Smolin. "ArXiv.org Quant-ph ArXiv:quant-ph/9604040." The Parity Bit in Quantum Cryptography. Phys.Rev. A54, Apr. 1996. Web. 25 Apr. 2016.
� Blumenthal, Matt. "Encryption: Strengths and Weakness." Encryption: Strengths and Weaknesses of Public-key Cryptography (n.d.): n. pag. Web. 20 Apr. 2016.
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Sources (Page 2) � Hjelme, Dag Roar, Lars Lyderson, and
Vadim Makarov. "Quantum Cryptography." SpringerReference (n.d.): n. pag. Arxiv. Arxiv, 7 Aug. 2011. Web. 1 Apr. 2016.
� Merriam-Webster. Merriam-Webster, n.d. Web. 25 Apr. 2016.
� "Quantum Cryptography." Wikipedia. Wikimedia Foundation, 21 Apr. 2016. Web. 25 Apr. 2016.
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Sources (Page 3)
� Scott, Thomas Jerry. "Cracking Keys with Current Intel CPUs." Cracking Keys with Current Intel CPUs -- Written by Thomas Jerry Scott. Tjscott, n.d. Web. 25 Apr. 2016.
� Tanenbaum, Andrew S. "Chapter 8." Computer Networks. Upper Saddle River, NJ: Prentice Hall PTR, 1996. 773-76. Print.
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Intel Key Cracking Speeds
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More about Keys
� Casual: 384-bits (Can be easily broken) � Commercial: 512-bits � Military: 1024-bit (Not breakable by
anyone on Earth) � Alien: 2048-bit (Not breakable by
anyone on other planets)
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