@inbook {1200421,
	title = {The Many Entropies in One-way Functions},
	booktitle = {Tutorials on the Foundations of Cryptography},
	year = {2017},
	pages = {159-217},
	publisher = {Springer, Yehuda Lindell, ed.},
	organization = {Springer, Yehuda Lindell, ed.},
	abstract = {
	Version History:\&nbsp;



	Earlier versions: May 2017:\&nbsp;ECCC TR 17-084



	Dec. 2017: ECCC TR 17-084 (revised)



	Computational analogues of information-theoretic notions have given rise to some of the most interesting phenomena in the theory of computation. For example, computational indistinguishability, Goldwasser and Micali [9], which is the computational analogue of statistical distance, enabled the bypassing of Shannon{\textquoteright}s impossibility results on perfectly secure encryption, and provided the basis for the computational theory of pseudorandomness. Pseudoentropy, H{\r a}stad, Impagliazzo, Levin, and Luby [17], a computational analogue of entropy, was the key to the fundamental result establishing the equivalence of pseudorandom generators and one-way functions, and has become a basic concept in complexity theory and cryptography.



	This tutorial discusses two rather recent computational notions of entropy, both of which can be easily found in any one-way function, the most basic cryptographic primitive. The first notion is next-block pseudoentropy, Haitner, Reingold, and Vadhan [14], a refinement of pseudoentropy that enables simpler and more ecient construction of pseudorandom generators. The second is inaccessible entropy, Haitner, Reingold, Vadhan, andWee [11], which relates to unforgeability and is used to construct simpler and more efficient universal one-way hash functions and statistically hiding commitments.

},
	url = {https://link.springer.com/chapter/10.1007/978-3-319-57048-8_4},
	author = {Iftach Haitner and Salil Vadhan}
}
