Akira Numayama

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We formalize the notion of several weakened random oracle models in order to capture which property of a hash function is crucial to prove the security of a cryptographic scheme. In particular, we focus on augmenting the random oracle with additional oracles that respectively return collisions, secondpreimages, and first-preimages. We study the security of(More)
Liskov proposed several weakened versions of the random oracle model, called weakened random oracle models (WROMs), to capture the vulnerability of ideal compression functions, which are expected to have the standard security of hash functions, i.e., collision resistance, second-preimage resistance, and one-wayness properties. The WROMs offer additional(More)
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