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Quantum search algorithm
Mejdrech, Lukáš ; Barto, Libor (advisor) ; Holub, Štěpán (referee)
In this work we study Grover's algorithm for quantum computers. This algorithm promises to search in an unstructured database in time comparable with a square root of the number of objects. A description of basic quantum computer principles is followed by the original Grover's formulation and a proof of the algorithm, as well as a later geometrical description of the algorithm. We also mention their suitability for educational purposes. We also include a description of the Grover's algorithm in a programming language, which makes it possible to simulate a quantum computing on classical computers.
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Lattice based cryptography
Divišová, Jana ; Barto, Libor (referee) ; Stanovský, David (advisor)
The aim of this work is several faces of lattices in cryptography. After the section in which we describe lattices in general and lattice problems, we turn to the lattice based cryptosystems. We describe their mathematical background and also formulations of encryption and decryption algorithms. In the next part we describe the usage of lattice in cryptanalysis. It is mainly attacks against knapsack system a solving hidden number problem. The signi cant part of this work is to compare two cryptosytems RSA a NTRU for the similar level of security. We compare the speed of encryption, decryption and key generation.
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