Barak Nehoran

dblp:339/8962 · DBLP profile ↗
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4ranked-venue papers
1as first author
4since 2021 · last 2025
0000-0001-7371-0829ORCID · corroborated

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Security and privacy · 2 · 2 since 2021Theory of computation · 2 · 1 first-author · 2 since 2021
YearPublicationVenuePosition
2025 Oracle Separation Between Quantum Commitments and Quantum One-Wayness
John Bostanci, Barak Nehoran
EUROCRYPT (7)3
2025 A General Quantum Duality for Representations of Groups with Applications to Quantum Money, Lightning, and Fire
abstract
Aaronson, Atia, and Susskind (2020) established that efficiently mapping between quantum states $|ψ\rangle$ and $|ϕ\rangle$ is computationally equivalent to distinguishing their superpositions $|ψ\rangle \pm |ϕ\rangle$. We generalize this insight into a broader duality principle, wherein manipulating quantum states in one basis is equivalent to extracting their value in a complementary basis. This general duality principle states that the ability to implement a unitary representation of a group is computationally equivalent to the ability to perform a Fourier subspace extraction from its irreducible representations. Building on our duality principle, we present the following applications: * We extend the construction of publicly-key quantum money of Zhandry (2024) from Abelian group actions to a construction of quantum lightning from non-Abelian group actions, and eliminate Zhandry's reliance on a black-box model for justifying security. Instead, we prove a direct reduction to a computational assumption -- the pre-action security of cryptographic group actions. Our construction is realizable with symmetric group actions, including those implicit in the McEliece cryptosystem. * We provide an alternative quantum lightning construction from one-way homomorphisms, with security holding under certain conditions. This scheme shows equivalence among four security notions: quantum lightning security, worst-case and average-case cloning security, and security against preparing a canonical state. * We formalize the notion of quantum fire, states that are efficiently clonable, but not efficiently telegraphable. These states can be spread like fire, provided they are kept alive quantumly and do not decohere. The only previously known construction relied on a unitary quantum oracle, whereas we present the first candidate construction of quantum fire using a classical oracle.
John Bostanci, Barak Nehoran, Mark Zhandry
STOC2
2024 Unconditionally Secure Commitments with Quantum Auxiliary Inputs
Tomoyuki Morimae, Barak Nehoran, Takashi Yamakawa
CRYPTO (7)2
2024 A Computational Separation Between Quantum No-Cloning and No-Telegraphing
abstract
Two of the fundamental no-go theorems of quantum information are the no-cloning theorem (that it is impossible to make copies of general quantum states) and the no-teleportation theorem (the prohibition on telegraphing, or sending quantum states over classical channels without pre-shared entanglement). They are known to be equivalent, in the sense that a collection of quantum states is telegraphable if and only if it is clonable. Our main result suggests that this is not the case when computational efficiency is considered. We give a collection of quantum states and quantum oracles relative to which these states are efficiently clonable but not efficiently telegraphable. Given that the opposite scenario is impossible (states that can be telegraphed can always trivially be cloned), this gives the most complete quantum oracle separation possible between these two important no-go properties. We additionally study the complexity class clonableQMA, a subset of QMA whose witnesses are efficiently clonable. As a consequence of our main result, we give a quantum oracle separation between clonableQMA and the class QCMA, whose witnesses are restricted to classical strings. We also propose a candidate oracle-free promise problem separating these classes. We finally demonstrate an application of clonable-but-not-telegraphable states to cryptography, by showing how such states can be used to protect against key exfiltration.
Barak Nehoran, Mark Zhandry
ITCS1