IA Scholar Query: Random Oracle Uninstantiability from Indistinguishability Obfuscation.
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Internet Archive Scholar query results feedeninfo@archive.orgTue, 13 Sep 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Classical Verification of Quantum Computations in Linear Time
https://scholar.archive.org/work/hza24tjplzeo3ln5eh36f3h6ni
In the quantum computation verification problem, a quantum server wants to convince a client that the output of evaluating a quantum circuit C is some result that it claims. This problem is considered very important both theoretically and practically in quantum computation [arXiv:1709.06984], [arXiv:1704.04487], [arXiv:1209.0449]. The client is considered to be limited in computational power, and one desirable property is that the client can be completely classical, which leads to the classical verification of quantum computation (CVQC) problem. In terms of the total time complexity, the fastest single-server CVQC protocol so far has complexity O(poly(κ)|C|^3) where |C| is the size of the circuit to be verified and κ is the security parameter, given by Mahadev [arXiv:1804.01082]. In this work, by developing new techniques, we give a new CVQC protocol with complexity O(poly(κ)|C|), which is significantly faster than existing protocols. Our protocol is secure in the quantum random oracle model [arXiv:1008.0931] assuming the existence of noisy trapdoor claw-free functions [arXiv:1804.00640], which are both extensively used assumptions in quantum cryptography. Along the way, we also give a new classical channel remote state preparation protocol for states in {|+_θ⟩=1/√(2)(|0⟩+e^iθπ/4|1⟩):θ∈{0,1⋯ 7}}, another basic primitive in quantum cryptography. Our protocol allows for parallel verifiable preparation of L independently random states in this form (up to a constant overall error and a possibly unbounded server-side simulator), and runs in only O(poly(κ)L) time and constant rounds; for comparison, existing works (even for possibly simpler state families) all require very large or unestimated time and round complexities [arXiv:1904.06320][arXiv:1904.06303][arXiv:2201.13445][arXiv:2201.13430].Jiayu Zhangwork_hza24tjplzeo3ln5eh36f3h6niTue, 13 Sep 2022 00:00:00 GMTQuantum cryptography with classical communication: parallel remote state preparation for copy-protection, verification, and more
https://scholar.archive.org/work/n2gcpkczwjgedgucslq7ulj3d4
Quantum mechanical effects have enabled the construction of cryptographic primitives that are impossible classically. For example, quantum copy-protection allows for a program to be encoded in a quantum state in such a way that the program can be evaluated, but not copied. Many of these cryptographic primitives are two-party protocols, where one party, Bob, has full quantum computational capabilities, and the other party, Alice, is only required to send random BB84 states to Bob. In this work, we show how such protocols can generically be converted to ones where Alice is fully classical, assuming that Bob cannot efficiently solve the LWE problem. In particular, this means that all communication between (classical) Alice and (quantum) Bob is classical, yet they can still make use of cryptographic primitives that would be impossible if both parties were classical. We apply this conversion procedure to obtain quantum cryptographic protocols with classical communication for unclonable encryption, copy-protection, computing on encrypted data, and verifiable blind delegated computation. The key technical ingredient for our result is a protocol for classically-instructed parallel remote state preparation of BB84 states. This is a multi-round protocol between (classical) Alice and (quantum polynomial-time) Bob that allows Alice to certify that Bob must have prepared n uniformly random BB84 states (up to a change of basis on his space). Furthermore, Alice knows which specific BB84 states Bob has prepared, while Bob himself does not. Hence, the situation at the end of this protocol is (almost) equivalent to one where Alice sent n random BB84 states to Bob. This allows us to replace the step of preparing and sending BB84 states in existing protocols by our remote-state preparation protocol in a generic and modular way.Alexandru Gheorghiu, Tony Metger, Alexander Porembawork_n2gcpkczwjgedgucslq7ulj3d4Tue, 06 Sep 2022 00:00:00 GMTQuantum copy-protection of compute-and-compare programs in the quantum random oracle model
https://scholar.archive.org/work/tvmnmmzaabbnzlgkcg3gk7bv74
Copy-protection allows a software distributor to encode a program in such a way that it can be evaluated on any input, yet it cannot be "pirated" - a notion that is impossible to achieve in a classical setting. Aaronson (CCC 2009) initiated the formal study of quantum copy-protection schemes, and speculated that quantum cryptography could offer a solution to the problem thanks to the quantum no-cloning theorem. In this work, we introduce a quantum copy-protection scheme for a large class of evasive functions known as "compute-and-compare programs" - a more expressive generalization of point functions. A compute-and-compare program 𝖢𝖢[f,y] is specified by a function f and a string y within its range: on input x, 𝖢𝖢[f,y] outputs 1, if f(x) = y, and 0 otherwise. We prove that our scheme achieves non-trivial security against fully malicious adversaries in the quantum random oracle model (QROM), which makes it the first copy-protection scheme to enjoy any level of provable security in a standard cryptographic model. As a complementary result, we show that the same scheme fulfils a weaker notion of software protection, called "secure software leasing", introduced very recently by Ananth and La Placa (eprint 2020), with a standard security bound in the QROM, i.e. guaranteeing negligible adversarial advantage. Finally, as a third contribution, we elucidate the relationship between unclonable encryption and copy-protection for multi-bit output point functions.Andrea Coladangelo, Christian Majenz, Alexander Porembawork_tvmnmmzaabbnzlgkcg3gk7bv74Mon, 31 Jan 2022 00:00:00 GMTRate-1 Incompressible Encryption from Standard Assumptions
https://scholar.archive.org/work/ryoh3oj4mrawjpcr2w5gz6jary
Incompressible encryption, recently proposed by Guan, Wichs and Zhandry (EUROCRYPT'22), is a novel encryption paradigm geared towards providing strong long-term security guarantees against adversaries with bounded long-term memory. Given that the adversary forgets just a small fraction of a ciphertext, this notion provides strong security for the message encrypted therein, even if, at some point in the future, the entire secret key is exposed. This comes at the price of having potentially very large ciphertexts. Thus, an important efficiency measure for incompressible encryption is the message-tociphertext ratio (also called the rate). Guan et al. provided a low-rate instantiation of this notion from standard assumptions and a rate-1 instantiation from indistinguishability obfuscation (iO). In this work, we propose a simple framework to build rate-1 incompressible encryption from standard assumptions. Our construction can be realized from, e.g. the DDH and additionally the DCR or the LWE assumptions.Pedro Branco, Nico Döttling, Jesko Dujmovicwork_ryoh3oj4mrawjpcr2w5gz6jary