F-HASH: Securing Hash Functions Using Feistel Chaining

The Feistel structure is well-known as a good structure for building block ciphers, due to its property of invertibility. It can be made non-invertible by fixing the left half of the input to 0, and by discarding the left half of the output bits. It then becomes suitable as a hash function construction. This paper uses the structure to build a hash function called F-Hash, which is immune to recent attack styles. In this paper, a more precise evaluation method, based upon conditional probability, is given

Revised: Block Cipher Based Hash Function Construction From PGV

Preneel, Govaerts, and Vandewalle[12] considered the 64 most basic ways to construct a hash function from a block cipher, and regarded 12 of these 64 schemes as secure. Black, Pogaway and Shrimpton[3] proved that, in black-box model, the 12 schemes that PGV singled out as secure really are secure and given tight upper and lower bounds on their collision resistance. And also they pointed out, by stepping outside of the Merkle-Damgard[5] approach to analysis, an additional 8 of the 64 schemes are just as collision resistant as the first group of schemes. In this paper we point out that the 12 compression functions that PGV singled out are free start collision resistant and others are not, the additional 8 compression functions are only fix start collision resistant as singled out by BRS, the hash functions based on those 20 schemes are fix start collision resistant, the upper bound of collision resistance and preimage resistant are given based on conditional probability of compression function, not based on assumption of random oracle model, the bounds have more practical value than the bounds given by BRS. In view point of collision resistant, the best 4 schemes are not among the 12 schemes singled by PGV, and among the 8 schemes point out by BRS, and block cipher E itself is the best compression to build a collision resistant hash function. At the end of the paper, two recommend structure of block cipher based hash function are given, and a prove of their securities are also given

No-compressing of quantum phase information

We raise a general question of quantum information theory whether the quantum phase information can be compressed and retrieved. A general qubit contains both amplitude and phase information, while an equatorial qubit contains only a phase information. We study whether it is possible to compress the phase information of n equatorial qubits into m general qubits with m being less than n, and still those information can be retrieved perfectly. We prove that this process is not allowed by quantum mechanics.Comment: 4 pages, 1 figur

4-Cyano-1-(4-nitro­benz­yl)pyridinium bis­(2-thioxo-1,3-dithiole-4,5-dithiol­ato-κ2 S 4,S 5)nickelate(III)

In the title salt, (C13H10N3O2)[Ni(C3S5)2], the NiIII cation is S,S′-chelated by two 2-thioxo-1,3-dithiole-4,5-dithiol­ate anions in a distorted square-planar geometry. The complex anion is approximately planar with a maximum deviation of 0.097 (1) Å. In the 1-(4-nitro­benz­yl)-4-cyano­pyridinium cation, the pyridine ring is twisted at a dihedral angle of 73.84 (16)° with respect to the benzene ring. π-π stacking is observed between nearly parallel [dihedral angle = 4.71 (7)°] dithiole and benzene rings, the centroid–centroid distance being 3.791 (2) Å

Enhancement of shot noise due to the fluctuation of Coulomb interaction

We have developed a theoretical formalism to investigate the contribution of fluctuation of Coulomb interaction to the shot noise based on Keldysh non-equilibrium Green's function method. We have applied our theory to study the behavior of dc shot noise of atomic junctions using the method of nonequilibrium Green's function combined with the density functional theory (NEGF-DFT). In particular, for atomic carbon wire consisting 4 carbon atoms in contact with two Al(100) electrodes, first principles calculation within NEGF-DFT formalism shows a negative differential resistance (NDR) region in I-V curve at finite bias due to the effective band bottom of the Al lead. We have calculated the shot noise spectrum using the conventional gauge invariant transport theory with Coulomb interaction considered explicitly on the Hartree level along with exchange and correlation effect. Although the Fano factor is enhanced from 0.6 to 0.8 in the NDR region, the expected super-Poissonian behavior in the NDR regionis not observed. When the fluctuation of Coulomb interaction is included in the shot noise, our numerical results show that the Fano factor is greater than one in the NDR region indicating a super-Poissonian behavior

Shaping Cultural and Creative Space: Beijing as a case study

Supported by research and policy reform, China’s creative and cultural industries have seen explosive growth in recent years and this rapid expansion is anticipated to have an unprecedented and far-reaching influence on the future of the country and its economy. Researchers from Cultural Development Institute (CDI) based at The Communication University of China (CUC) and The College of Fine Arts (COFA) at the University of New South Wales (UNSW) present recently generated data and discuss Beijing as a case study to provide an informed overview of the recent proliferation of art parks and creative clusters in the city