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Definition
Computational complexity theory is the study of the minimal resources needed to solve computational problems. In particular, it aims to distinguish between those problems that possess efficient algorithms (the “easy” problems) and those that are inherently intractable (the “hard” problems). Thus computational complexity provides a foundation for most of modern cryptography, where the aim is to design cryptosystems that are “easy to use” but “hard to break” (Security [Computational, Unconditional]).
Theory
Running Time. The most basic resource studied in computational complexity is running time – the number of basic “steps” taken by an algorithm (Other resources, such as space[i.e., memory usage], are also studied, but they will not be discussed here). To make this precise, one needs to fix a model of...
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Recommended Reading
Arora S, Barak B (2009) Computational complexity: a modern approach. Cambridge University Press, Cambridge
Garey MR, Johnson DS (1979) Computers and intractability: a guide to the theory of NP-completeness. W.H. Freeman and Company, San Francisco
Goldreich O (2008) Computational complexity: a conceptual perspective. Cambridge University Press, Cambridge
Goldreich O (2001) Foundations of cryptography: basic tools. Cambridge University Press, Cambridge
Goldreich O (2004) Foundations of cryptography. Vol II: basic applications. Cambridge University Press, Cambridge
Sipser M (1997) Introduction to the theory of computation. PWS Publishing, Boston
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Vadhan, S. (2011). Computational Complexity. In: van Tilborg, H.C.A., Jajodia, S. (eds) Encyclopedia of Cryptography and Security. Springer, Boston, MA. https://doi.org/10.1007/978-1-4419-5906-5_442
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DOI: https://doi.org/10.1007/978-1-4419-5906-5_442
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