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61.
The Visual multi-secret sharing (VMSS) scheme is characterized by encoding several secret images into a set of noise-like shares. Most existing VMSS meth- ods have to distort shares to embed additional secret im- ages. As a result, the quality of the decoded original secret image is degraded. This paper proposes a folding-up op- eration based VMSS scheme, which is able to encode one secret image and a group of tag images into shares. The secret image is revealed by stacking all shares, and fold- ing up each chosen share discloses the tag image. The proposed scheme encodes tag images without affecting the quality of the reconstructed secret image. The quality of the decoded secret image is equal to that of the conven- tional Visual secret sharing (VSS) scheme. The superiority of the proposed method is experimental verified. 相似文献
62.
A. Stern 《Physics letters. A》2011,375(25):2498-2502
We discuss alternatives to the usual quantization of a relativistic particle which result in discrete spectra for position and time operators. 相似文献
63.
64.
From the perspective of information theory and cryptography, the security of two quantum dialogue protocols and a bidirectional
quantum secure direct communication (QSDC) protocol was analyzed, and it was pointed out that the transmitted information
would be partly leaked out in them. That is, any eavesdropper can elicit some information about the secrets from the public
annunciations of the legal users. This phenomenon should have been strictly forbidden in a quantum secure communication. In
fact, this problem exists in quite a few recent proposals and, therefore, it deserves more research attention in the following
related study.
Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA01Z419), the National
Natural Science Foundation of China (Grant Nos. 90604023 and 60373059), the National Research Foundation for the Doctoral
Program of Higher Education of China (Grant No. 20040013007), the National Laboratory for Modern Communications Science Foundation
of China (Grant No. 9140C1101010601), the Natural Science Foundation of Beijing (Grant No. 4072020) and the ISN Open Foundation 相似文献
65.
Threshold Visual Cryptography Schemes with Specified Whiteness Levels of Reconstructed Pixels 总被引:6,自引:0,他引:6
In 1994, Naor and Shamir introduced an unconditionally secure method for encoding black and white images. This method, known as a threshold visual cryptography scheme (VCS), has the benefit of requiring no cryptographic computation on the part of the decoders. In a
-VCS, a share, in the form of a transparency, is given to ">n users. Any ">k users can recover the secret simply by stacking transparencies, but ">k-1 users can gain no information about the secret whatsoever.In this paper, we first explore the issue of contrast, by demonstrating that the current definitions are inadequate, and by providing an alternative definition. This new definition motivates an examination of minimizing pixel expansion subject to fixing the VCS parameters ">h and ">l. New bounds on pixel expansion are introduced, and connections between these bounds are examined. The best bound presented is tighter than any previous bound. An analysis of connections between (2, ">n) schemes and designs such as BIBD's, PBD's, and (">r, )-designs is performed. Also, an integer linear program is provided whose solution exactly determines the minimum pixel expansion of a (2, ">n)-VCS with specified ">h and >l. 相似文献
66.
This paper is concerned with algorithms for computing in the divisor class group of a nonsingular plane curve of the form which has only one point at infinity. Divisors are represented as ideals, and an ideal reduction algorithm based on lattice reduction is given. We obtain a unique representative for each divisor class and the algorithms for addition and reduction of divisors run in polynomial time. An algorithm is also given for solving the discrete logarithm problem when the curve is defined over a finite field.
67.
本文基于椭圆曲线上的双线性对性质,提出了一个基于身份的带凭证部分委托代理多重签名方案,该方案具有强不可伪造性、强不可否认性、强可识别性和预防误用性. 相似文献
68.
69.
This paper presents the concept of a Dielectric-lined Multiwave Cerenkov Generator(DMWCG) producing high power millimeter waves, which is investigated with a two and one half dimensional(
) electromagnetic relativistic Particle-in-Cell(PIC) simulation code. It is showed that the DMWCG can operate in a lower diode-voltage regime with much higher radiation efficiency as compared with the usual Multiwave Cerenkov Generator(MWCG). The simulation work indicates both the downshift of the wave frequency in the presence of the dielectric liner and the existence of the optima for the permittivity of the liner as well as for the magnitude of the guiding magnetic field. The required intensity of the guiding field is reduced with the introducing of the liner. The radiation is generated at the dominant frequency of 31.5GHz. The power level of 1.5GW is achieved, with radiation efficiency up to 15%. The features of parameter dependency are presented. And reasonable explanation is put forward. In addition, the enhanced propagation of the electron beam is studied in the presence of the dielectric liner. 相似文献
70.
S. Karshenboim U. Jentschura V. Ivanov G. Soff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(3):209-215
We present an analytical evaluation of radiative corrections in exotic atoms induced by the one-loop electronic vacuum polarization.
We evaluate corrections to the energy levels, to the wave function (at the origin) and to the hyperfine structure. We treat
all corrections analytically within a non-relativistic approximation. Agreement is found with a few available numerical results.
The analytical treatment allows to determine the asymptotic forms of the corrections in the limit of a small atomic radius,
which for the atomic systems considered corresponds to a large mass of the constituent particle as compared to the electron
mass. The asymptotics can be verified using the effective charge approach.
Received: 28 January 1998 / Accepted: 13 March 1998 相似文献