377 research outputs found
CRPSF and NTRU Signatures over cyclotomic fields
Classical NTRUEncrypt is one of the fastest known lattice-based encryption schemes. Its counterpart, NTRUSign, also has many advantages, such as moderate key sizes, high efficiency and potential of resisting attacks from quantum computers. However, like classical NTRUEncrypt, the security of NTRUSign is also heuristic. Whether we can relate the security of NTRUSign to the worst-case lattice problems like NTRUEncrypt is still an open problem.
Our main contribution is that we propose a detailed construction of Collision Resistance Preimage Sampleable Functions CRPSF over any cyclotomic field based on NTRU. By using GPV\u27s construction, we can give a provably secure NTRU Signature scheme NTRUSign, which is strongly existentially unforgeable under adaptive chosen-message attacks in the quantum random oracle model. The security of CRPSF NTRUSign is reduced to the corresponding ring small integer solution problem Ring-SIS. More precisely, the security of our scheme is based on the worst-case approximate shortest independent vectors problem SIVP over ideal lattices. For any fixed cyclotomic field, we give a probabilistic polynomial time PPT key generation algorithm which shows how to extend the secret key of NTRUEncrypt to the secret key of NTRUSign. This algorithm is important for constructions of many cryptographic primitives based on NTRU, for example, CRPSF, NTRUSign, identity-based encryption and identity-based signature.
We also delve back into former construction of NTRUEncrypt, give a much tighter reduction from decision dual-Ring-LWE problem (where the secret is chosen form the codifferent ideal) to decision primal-Ring-LWE problem (where the secret is chosen form the ring of integers) and give a provably secure NTRUEncrypt over any cyclotomic ring. Some useful results about -ary lattices, regularity and uniformity of distribution of the public keys of NTRUEncrypt are also extended to more general algebraic fields
Spin Wave Magnetic NanoFabric: A New Approach to Spin-based Logic Circuitry
We propose and describe a magnetic NanoFabric which provides a route to
building reconfigurable spin-based logic circuits compatible with conventional
electron-based devices. A distinctive feature of the proposed NanoFabric is
that a bit of information is encoded into the phase of the spin wave signal. It
makes possible to transmit information without the use of electric current and
utilize wave interference for useful logic functionality. The basic elements
include voltage-to-spin wave and wave-to-voltage converters, spin waveguides, a
modulator, and a magnetoelectric cell. As an example of a magnetoelectric cell,
we consider a two-phase piezoelectric-piezomagnetic system, where the spin wave
signal modulation is due to the stress-induced anisotropy caused by the applied
electric field. The performance of the basic elements is illustrated by
experimental data and results of numerical modeling. The combination of the
basic elements let us construct magnetic circuits for NOT and Majority logic
gates. Logic gates AND, OR, NAND and NOR are shown to be constructed as the
combination of NOT and a reconfigurable Majority gates. The examples of
computational architectures such as Cellular Automata, Cellular Nonlinear
Network and Field Programmable Gate Array are described. The main advantage of
the proposed NanoFabric is in the ability to realize logic gates with less
number of devices than it required for CMOS-based circuits. Potentially, the
area of the elementary reconfigurable Majority gate can be scaled down to
0.1um2. The disadvantages and limitations of the proposed NanoFabric are
discussed
Efficient provable-secure NTRUEncrypt over any cyclotomic field
NTRUEncrypt is a fast lattice-based cryptosystem and a probable alternative of the existing public key schemes. The existing provable-secure NTRUEncrypts are limited by the cyclotomic field it works on - the prime-power cyclotomic field. This is worth worrying, due to the subfield attack methods proposed in . Also, the module used in computation and security parameters rely heavily on the choice of plaintext space. These disadvantages restrict the applications of NTRUEncrypt.
In this paper, we give a new provable secure NTRUEncrypt in standard model under canonical embedding over any cyclotomic field. We give an reduction from a simple variant of RLWE - an error distribution discretized version of RLWE, hence from worst-case ideal lattice problems, to our NTRUEncrypt. In particular, we get a union bound for reduction parameters and module for all choices of plaintext space, so that our NTRUEncrypt can send more encrypted bits in one encrypt process with higher efficiency and stronger security. Furthermore, our scheme\u27s decryption algorithm succeeds with probability 1-n^{\o(\sqrt{n\log n})} comparing with the previous works\u27 1-n^{-\o(1)}, making our scheme more practical in theory
Watermarking PRFs from Lattices: Public Extract and Collusion Resistant
A software watermarking scheme enables one to embed a ``mark (i.e., a message) into a program without significantly changing the functionality. Moreover, any removal of the watermark from a marked program is futile without significantly changing the functionality of the program. At present, the construction of software watermarking mainly focuses on watermarking pseudorandom functions (PRFs), watermarking public key encryption, watermarking signature, etc.
In this work, we construct new watermarking PRFs from lattices which provide collusion resistant and public extraction. Our schemes are the first to simultaneously achieve all of these properties. The key to the success of our new constructions lies in two parts. First, we relax the notion of functionality-preserving. In general, we require that a marked program (approximately) preserve the input/output behavior of the original program. For our scheme, the output circuit is divided into two parts, one for PRF output and the other for auxiliary functions. As a result, we only require the PRF output circuit to satisfy functionality-preserving. Second, the marking method we use is essentially different form the previous scheme. In general, the mark program will change the output of some special point. The extraction algorithm determines whether the circuit is marked by determining whether the output of some special points has been changed. In our schemes, we use the constrained signature to mark a PRF circuit
RainDiffusion:When Unsupervised Learning Meets Diffusion Models for Real-world Image Deraining
What will happen when unsupervised learning meets diffusion models for
real-world image deraining? To answer it, we propose RainDiffusion, the first
unsupervised image deraining paradigm based on diffusion models. Beyond the
traditional unsupervised wisdom of image deraining, RainDiffusion introduces
stable training of unpaired real-world data instead of weakly adversarial
training. RainDiffusion consists of two cooperative branches: Non-diffusive
Translation Branch (NTB) and Diffusive Translation Branch (DTB). NTB exploits a
cycle-consistent architecture to bypass the difficulty in unpaired training of
standard diffusion models by generating initial clean/rainy image pairs. DTB
leverages two conditional diffusion modules to progressively refine the desired
output with initial image pairs and diffusive generative prior, to obtain a
better generalization ability of deraining and rain generation. Rain-Diffusion
is a non adversarial training paradigm, serving as a new standard bar for
real-world image deraining. Extensive experiments confirm the superiority of
our RainDiffusion over un/semi-supervised methods and show its competitive
advantages over fully-supervised ones.Comment: 9 page
A New Method of Constructing a Lattice Basis and Its Applications to Cryptanalyse Short Exponent RSA
We provide a new method of constructing an optimal
lattice. Applying our method to the cryptanalysis of the short exponent
RSA, we obtain our results which extend Boneh and Durfee's work. Our
attack methods are based on a generalization to multivariate modular polynomial
equation. The results illustrate the fact that one should be careful
when using RSA key generation process with special parameters
Repudiable Ring Signature: Stronger Security and Logarithmic-Size
Ring signatures allow a person to generate a signature on behalf of an ad hoc group, and can hide the true identity of the signer among the group. Repudiable ring signatures are the more strongly defined ring signatures, which can allow every non-signer to prove to others that the signature was not generated by himself.
This paper has two main areas of focus. First, we propose a new requirement for repudiable ring signatures, which is that no one can forge a valid repudiation for others. Second, as a breakthrough, we present the first logarithmic-size repudiable ring signatures which do not rely on a trusted setup or the random oracle model. Specifically, our scheme can be instantiated from standard assumptions and the size of signatures and repudiations only grows logarithmically in the number of ring members.
Besides, our scheme also provides a new construction of logarithmic-size standard ring signatures
Reverse Outsourcing: Reduce the Cloud\u27s Workload in Outsourced Attribute-Based Encryption Scheme
Attribute-based encryption (ABE) is a cryptographic technique known for ensuring fine-grained access control on encrypted data. One of the main drawbacks of ABE is the time required to decrypt the ciphertext is considerably expensive, since it grows with the complexity of access policy. Green et al. [USENIX, 2011] provided the outsourced ABE scheme, in which most computational overhead of ciphertext decryption is outsourced from end user to the cloud. However, their method inevitably increases the computational burden of the cloud. While millions of users are enjoying cloud computing services simultaneously, it may cause huge congestion and latency.
In this paper, we propose a heuristic primitive called reverse outsourcing to reduce the cloud\u27s workload. Specifically, the cloud is allowed to transform the ciphertext decryption outsourced by the end user into several computing tasks and dispatches them to idle users, who have some smart devices connected to the internet but not in use. These devices can provide computing resources for the cloud, just like the cloud hires many employees to complete the computing work. Besides, the computing results returned by the idle users should be verified by the cloud.
We propose a reverse outsourced CP-ABE scheme in the rational idle user model, where idle users will be rewarded by the cloud after returning the correct computing results and they prefer to get rewards instead of saving resources. According to the Nash equilibrium, we prove that the best strategy for idle users is to follow our protocol honestly, because the probability of deceiving the cloud with incorrect computing results is negligible. Therefore, in our scheme, most computational overhead of ciphertext decryption is shifted from the cloud to idle users, leaving a constant number of operations for the cloud
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