428 research outputs found
Copy-Protection from UPO, Revisited
No full textQuantum copy-protection is a foundational notion in quantum cryptography that leverages the governing principles of quantum mechanics to tackle the problem of software anti-piracy. Despite progress in recent years, precisely characterizing the class of functionalities that can be copy-protected is still not well understood.
Two recent works, by [Coladangelo and Gunn, STOC 2024] and [Ananth and Behera, CRYPTO 2024, showed that puncturable functionalities can be copy-protected. Both works have significant caveats with regard to the underlying cryptographic assumptions and additionally restrict the output length of the functionalities to be copy-protected. In this work, we make progress towards simultaneously addressing both caveats. We show the following:
- Revisiting Unclonable Puncturable Obfuscation (UPO): We revisit the notion of UPO introduced by [Ananth and Behera, CRYPTO 2024]. We present a new approach to construct UPO and a variant of UPO, called independent-secure UPO. Unlike UPO, we show how to base the latter notion on well-studied assumptions.
- Copy-Protection from Independent-secure UPO: Assuming independent-secure UPO, we show that any m-bit, for m ≥ 2, puncturable functionality can be copy-protected.
- Copy-Protection from UPO: Assuming UPO, we show that any 1-bit puncturable functionality can be copy-protected. The security of copy-protection holds against identical challenge distributions
FDI Spillovers, Innovation and the Role of Industrial Clusters: Evidence from Innovative Indian Manufacturing Firms
No full text© 2025, Elsevier B.V. The attached document (embargoed until 08/09/2026) is an author produced version of a paper published in Economic Modelling uploaded in accordance with the publisher’s self-archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it
A Study of Mechanisms to Engineer Fine Scale Alpha Phase Precipitation in Beta Titanium Alloy, Beta 21S
No full textMetastable b-Ti alloys are titanium alloys with sufficient b stabilizer alloying additions such that it's possible to retain single b phase at room temperature. These alloys are of great advantage compared to a/b alloys since they are easily cold rolled, strip produced and can attain excellent mechanical properties upon age hardening. Beta 21S, a relatively new b titanium alloy in addition to these general advantages is known to possess excellent oxidation and corrosion resistance at elevated temperatures. A homogeneous distribution of fine sized a precipitates in the parent b matrix is known to provide good combination of strength, ductility and fracture toughness. The current work focuses on a study of different mechanisms to engineer homogeneously distributed fine sized a precipitates in the b matrix. The precipitation of metastable phases upon low temperature aging and their influence on a precipitation is studied in detail. The precipitation sequence on direct aging above the w solvus temperature is also assessed. The structural and compositional evolution of precipitate phase is determined using multiple characterization tools. The possibility of occurrence of other non-classical precipitation mechanisms that do not require heterogeneous nucleation sites are also analyzed. Lastly, the influence of interstitial element, oxygen on a precipitation during the oxidation of Beta 21S has been determined. The ingress of oxygen and its influence on microstructure have also been correlated to measured mechanical properties
Molecular Dynamics simulations reveal the role of membrane cholesterol in the pore forming pathway of Cytolysin A
No full textWe investigate the interactions of pore-forming toxins (PFTs) with cholesterol-rich
membranes through atomistic molecular dynamics simulations. The PFT of interest
is Cytolysin A (ClyA or HlyE). Cytolysin A (ClyA), an pore-forming protein expressed
by E. Coli as a water-soluble monomer, undergoes a drastic conformational
change from its water-soluble monomeric state to the membrane-inserted protomeric
state which subsequently oligomerizes to form a dodecameric pore. Many PFTs have
their specificity towards certain receptors, present in the membrane. Recent single
molecule experiments show that the conversion rate from the water-soluble monomer
to the membrane-inserted protomer increases in the presence of cholesterol. Further,
lysis experiments in RBCs have a half-life time that was orders of magnitude smaller
than that of RBCs when cholesterol is removed. Consequently, cholesterol was established
as factor in enhancing the lytic activity of ClyA. However, the precise molecular
aspects of the interactions between cholesterol and ClyA during pore formation are not
well understood.
Using all-atom molecular dynamics simulations ranging from 0.5 - 0.9 s, we
study a single membrane-inserted protomer, a dimer (two protomers) and the dodecameric
ClyA pore embedded in a DOPC+30% cholesterol bilayer. In the single
membrane-inserted protomer, high cholesterol occupancy was observed around the
transmembrane residues of N-terminus which form part of a “CRAC” (a region with
high cholesterol affinity) motif and also around residues of the -tongue. Although
high cholesterol occupancy sites were not observed near the N-terminus in the dimer
simulations, a cholesterol molecule was preferentially located in the pocket formed
between two adjacent -tongues of the dimer. Cholesterol spent 97% of the simulation
time (600 ns) inside this pocket sampling two major orientations. Energies
of two conformations were reported from docking simulations. Formations of transmembrane
water channels were observed in both single membrane inserted and dimer
ClyA simulations. From the dodecameric pore simulations, density map showed regions
of high cholesterol population between the -tongue pockets and mobility map
indicated slower cholesterol in the vicinity of the pore as compared to bulk. Our
simulations elucidate specific interactions with cholesterol that could stabilize both
the single membrane inserted protomeric state as well as the dodecameric pore. Free energy computations were performed with only the -helix at different orientations
in membranes with and without cholesterol. A well defined minima is observed in
the presence of cholesterol when compared with the broad minima in the absence of
cholesterol. This study has provided molecular level insight into the role of cholesterol
in regulating the pore forming activity of ClyA establishing for the first time a specific
cholesterol recognizing residues in an -PFT. The identification of receptor specific
segments in ClyA could potentially add to the designing of ‘anti-toxin’ therapeutic
remedies
Almost Public Quantum Coins
No full textIn a quantum money scheme, a bank can issue money that users cannot counterfeit. Similar to bills of paper money, most quantum money schemes assign a unique serial number to each money state, thus potentially compromising the privacy of the users of quantum money. However in a quantum coins scheme, just like the traditional currency coin scheme, all the money states are exact copies of each other, providing a better level of privacy for the users. A quantum money scheme can be private, i.e., only the bank can verify the money states, or public, meaning anyone can verify. In this work, we propose a way to lift any private quantum coin scheme -- which is known to exist based on the existence of one-way functions, due to Ji, Liu, and Song (CRYPTO\u2718) -- to a scheme that closely resembles a public quantum coin scheme. Verification of a new coin is done by comparing it to the coins the user already possesses, by using a projector on to the symmetric subspace. No public coin scheme was known prior to this work. It is also the first construction that is very close to a public quantum money scheme and is provably secure based on standard assumptions. Finally, the lifting technique, when instantiated with the private quantum coins scheme~\cite{MS10}, gives rise to the first construction that is close to an inefficient unconditionally secure public quantum money scheme
Closed Form HJB Solution for Path Planning of a Robot Manipulator with Warehousing Applications
No full textReal-time optimal path planning for robotic manipulations in task space is a very fundamental and important problem. In this paper, the problem of generating robot trajectories in an obstacle-ridden environment is formulated under an optimal control framework using Hamilton-Jacobi-Bellman (HJB) equation. The novel contribution of this paper is that a closed form HJB control solution (a necessary and sufficient condition for global optimality of a control solution with respect to a cost function) has been achieved for generating real-time optimal trajectories for a robot manipulator. In contrast with the decoupled end-effector path planning and subsequent trajectory generation, the proposed scheme can exploit sensory input for real-time trajectory generation where the end-effector path as well as the joint trajectory is recomputed online while satisfying the real-time constraints. The stability and the performance of the proposed control framework is shown theoretically via Lyapunov approach and also verified experimentally using a 6 degrees of freedom (DOF) Universal Robot (UR) 10 robot manipulator. It is shown that a significant saving in cost metrics can be obtained over similar trajectory generation approaches from the state-of-the-art with obstacle-ridden environment and also has better performance in high speed tracking applications. Warehouse applications of the proposed scheme in case of static and dynamic targets with respect to the robot manipulator is also included.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Learning & Autonomous Contro
Quantum to classical one-way function and its applications in quantum money authentication
No full textIn 2013, Farid and Vasiliev [arXiv:1310.4922 [quant-ph]] for the first time proposed a way to construct a protocol for the realisation of “Classical to Quantum” one-way hash function, a derivative of the quantum one-way function as defined by Gottesman and Chuang [Technical Report arXiv:quant-ph/0105032] and used it for constructing quantum digital signatures. We, on the other hand, for the first time, propose the idea of a different kind of one-way function, which is “quantum-classical” in nature, that is, it takes an n-qubit quantum state of a definite kind as its input and produces a classical output. We formally define such a one-way function and propose a way to construct and realise it. The proposed one-way function turns out to be very useful in authenticating a quantum state in any quantum money scheme, and so we can construct many different quantum money schemes based on such a one-way function. Later in the paper, we also give explicit constructions of some interesting quantum money schemes like quantum bitcoins and quantum currency schemes, solely based on the proposed one-way function. The security of such schemes can be explained on the basis of the security of the underlying one-way functions
A Modular Approach to Unclonable Cryptography
No full textWe explore a new pathway to designing unclonable cryptographic primitives. We propose a new notion called unclonable puncturable obfuscation (UPO) and study its implications for unclonable cryptography. Using UPO, we present modular (and in some cases, arguably, simple) constructions of many primitives in unclonable cryptography, including, public-key quantum money, quantum copy-protection for many classes of functionalities, unclonable encryption, and single-decryption encryption.
Notably, we obtain the following new results assuming the existence of UPO:
- We show that any cryptographic functionality can be copy-protected as long as this functionality satisfies a notion of security, which we term as puncturable security. Prior feasibility results focused on copy-protecting specific cryptographic functionalities.
- We show that copy-protection exists for any class of evasive functions as long as the associated distribution satisfies a preimage-sampleability condition. Prior works demonstrated copy-protection for point functions, which follows as a special case of our result.
- We show that unclonable encryption exists in the plain model. Prior works demonstrated feasibility results in the quantum random oracle model.
We put forward a candidate construction of UPO and prove two notions of security, each based on the existence of (post-quantum) sub-exponentially secure indistinguishability obfuscation and one-way functions, the quantum hardness of learning with errors, and a new conjecture called simultaneous inner product conjecture
A Modular Approach to Unclonable Cryptography
No full textWe explore a new pathway to designing unclonable cryptographic primitives. We
propose a new notion called unclonable puncturable obfuscation (UPO) and study
its implications for unclonable cryptography. Using UPO, we present modular
(and arguably, simple) constructions of many primitives in unclonable
cryptography, including public-key quantum money, quantum copy-protection for
many classes of functionalities, unclonable encryption, and single-decryption
encryption. Notably, we obtain the following new results assuming the existence
of UPO: We show that any cryptographic functionality can be copy-protected as
long as this functionality satisfies a notion of security, which we term as
puncturable security. Prior feasibility results focused on copy-protecting
specific cryptographic functionalities. We show that copy-protection exists for
any class of evasive functions as long as the associated distribution satisfies
a preimage-sampleability condition. Prior works demonstrated copy-protection
for point functions, which follows as a special case of our result. We show
that unclonable encryption exists in the plain model. Prior works demonstrated
feasibility results in the quantum random oracle model. We put forward a
candidate construction of UPO and prove two notions of security, each based on
the existence of (post-quantum) sub-exponentially secure indistinguishability
obfuscation and one-way functions, the quantum hardness of learning with
errors, and a new conjecture called simultaneous inner product conjecture.Comment: Upgraded the construction of generalized UPO from QSIO by replacing
the requirement of private-key unclonable encryption with leakage-resilient
security with just private-key unclonable encryption for bit
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