IACR News item: 23 August 2011
PhD Database
Chun-Yuan Hsiao
BUTTERFLY EFFECT IN CRYPTOGRAPHY: CONSEQUENCES OF CHANGES IN DEFINITIONS
foundations
Modern cryptography places a great deal of emphasis on de nitions, because a precise\r\nde nition formalizes our intuition about a cryptographic primitive.\r\n\r\nThis dissertation consists of two parts. The first part demonstrates the importance of\r\nde nitional precision by examining a previously overlooked subtlety in de ning a widelyused\r\nprimitive: the Collision Resistant Hash Function, or CRHF. The subtlety lies in the\r\nmethod by which the CRHF key is generated: namely, whether a trusted party needs to\r\nperform key generation (the \"secret-coin\" variant), or whether any public random string\r\ncan be used as the key (the \"public-coin\" variant). Adding a new technique to the so-called \"black-box separation\" methodology, this thesis shows that these two variants of CRHF, which were sometimes used interchangeably, are actually distinct in general. However, they are also equivalent under certain conditions; the thesis identi es a precise and broad set of such conditions.\r\n\r\nThe second part of this dissertation investigates two known de nitions of entropy. Shannon has shown the equivalence of these two de nitions by proving that the shortest compression length of [...]
BUTTERFLY EFFECT IN CRYPTOGRAPHY: CONSEQUENCES OF CHANGES IN DEFINITIONS
foundations
Modern cryptography places a great deal of emphasis on de nitions, because a precise\r\nde nition formalizes our intuition about a cryptographic primitive.\r\n\r\nThis dissertation consists of two parts. The first part demonstrates the importance of\r\nde nitional precision by examining a previously overlooked subtlety in de ning a widelyused\r\nprimitive: the Collision Resistant Hash Function, or CRHF. The subtlety lies in the\r\nmethod by which the CRHF key is generated: namely, whether a trusted party needs to\r\nperform key generation (the \"secret-coin\" variant), or whether any public random string\r\ncan be used as the key (the \"public-coin\" variant). Adding a new technique to the so-called \"black-box separation\" methodology, this thesis shows that these two variants of CRHF, which were sometimes used interchangeably, are actually distinct in general. However, they are also equivalent under certain conditions; the thesis identi es a precise and broad set of such conditions.\r\n\r\nThe second part of this dissertation investigates two known de nitions of entropy. Shannon has shown the equivalence of these two de nitions by proving that the shortest compression length of [...]
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