**Lecturenotes**

1. A very brief history of secrecy

**Heidelberg, April 2013**

The handwritten notes are half-baked and may contain errors. Please let me know if you find one.

- Lecture 1 History of cryptography, key distribution problem, possible solutions
- Lecture 2 Modular arithmetic, Euclid's algorithm, Euler's theorem, RSA, quantum factoring.
- Lecture 3 Distinguishability of non-orthogonal states, entanglement, quantum key distribution
- Lecture 4 Statistical distance, security defined, predictability, privacy amplification
- Lecture 5 Post-quantum cryptography, device independence, practicalities

**Q&A**

- I am glad you asked qustions about the foundations of quantum theory. When asked whether physics describes reality or merely our perception of reality I alluded to the paper "The Quantum State Cannot be Interpreted Statistically" by Pusey, Barrett and Rudolph. A good starting point to investigate this issue further is this blog by Matt Leifer. You find the relevant links in the text.
- Wikipedia has good entries on the extended Euclidean algorthm and Bézout's identity.
- More on Public Key Cryptography and RSA

**Supplementary Material**

- Less reality more security by A. Ekert, Physics World, Sep 2009.
- About cryptography, classical and quantum by A. Ekert, +Plus Magazine.
- Beyond the Quantum Horizon by D. Deutsch and A. Ekert, Scientific American, Sep 2012.
- The Limits of Quantum Computers, by S. Aaronson, Scientific American, Mar 2008.
- Physical Limits of Computation by C.H. Bennett and R. Landauer, Scientific American, Jul 1985.