It is well known that the random oracle model is not sound in the sense that there exist cryptographic systems that are secure in the random oracle model but when instantiated by any family of hash functions become insecure. However, all known separation results require the attacker to send an appropriately crafted message to the challenger in order to break security. Thus, this leaves open the...

QROM (quantum random oracle model), introduced by Boneh et al. (Asiacrypt 2011), captures all generic algorithms. However, it fails to describe non-uniform quantum algorithms with preprocessing power, which receives a piece of bounded classical or advice. As are largely believed be the right model for attackers, starting from work Nayebi, Aaronson, Belovs, and Trevisan (QIC 2015), line works in...

The random-oracle model by Bellare and Rogaway (CCS’93) is an indispensable tool for the security analysis of practical cryptographic protocols. However, the traditional random-oracle model fails to guarantee security when a protocol is composed with arbitrary protocols that use the same random oracle. Canetti, Jain, and Scafuro (CCS’14) put forth a global but non-programmable random oracle in ...

Boneh et al. [6] proposed an identification protocol in Asiacrypt 2011 that is secure in the classical random oracle model but insecure in the quantum random oracle model. This paper finds that a constant parameter plays a significant role in the security of the protocol and the variation of this parameter changes the security greatly. Therefore, an improved identification protocol that replace...

We consider the uniform BSS model of computation where the machines can perform additions, multiplications, and tests of the form x ≥ 0. The oracle machines can also check whether a tuple of real numbers belongs to a given oracle set O or not. We construct oracles such that the classes P and DNP relative to these oracles are equal or not equal.

In this paper, we present a hybrid encryption scheme that is chosen ciphertext secure in the quantum random oracle model. Our scheme is a combination of an asymmetric and a symmetric encryption scheme that are secure in a weak sense. It is a slight modification of the Fujisaki-Okamoto transform that is secure against classical adversaries. In addition, we modify the OAEP-cryptosystem and prove ...