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There have been several works for studying the security of CRT-RSA with small CRT exponents d p and d q by using lattice-based Coppersmith's method. Thus far, two attack scenarios have been mainly studied: (1) d q is small with unbalanced prime factors p ≪ q. (2) Both d p and d q are small for balanced p ≈ q. The best attacks for the both scenarios were proposed by Takayasu-Lu-Peng (Eurocrypt'17, Journal of Cryptology'19) and the attack conditions are much better than the other known attacks. Although the attacks have been very useful for studying the security of CRT-RSA, the structures of their proposed lattices are not well understood. In this paper, to further study the security of CRT-RSA, we first define a generalized attack scenario to unify the previous ones. Specifically, all p , q , d p , and d q can be of arbitrary sizes. Furthermore, we propose improved attacks in this paper when d p and/or p is sufficiently small. Technically, we construct a lattice whose basis vectors are chosen flexibly depending on the sizes of p , q , d p , and d q. Since the attack scenarios (1) and (2) are simpler than our general scenario, the previous Takayasu-Lu-Peng's lattices are simple special cases of ours. We are able to achieve the flexible lattice constructions by exploiting implicit but essential structures of Takayasu-Lu-Peng's lattices. We check the validity of our proposed attacks by computer experiments. We believe that the deeper understanding of the lattice structures will be useful for studying the security of CRT-RSA even in other scenarios. [ABSTRACT FROM AUTHOR]

Floating ring bearing has the advantages of simple structure and high operating speed and is widely used in turbocharger and aero-engine. However, many harsh working conditions cause the floating ring bearing to produce starved lubrication and failures. Here, we investigated the starved lubrication characteristics of floating ring bearing via theoretical modeling and numerical simulation. We first established a theoretical model of starved-boundary lubrication based on the Reynolds equation for floating ring bearing. And meanwhile, an oil-film ratio coefficient is introduced into the theoretical model to reflect the degree of starved lubrication. We then analyzed the influence of inlet-boundary conditions (flow rate, oil-film thickness) on the starved-lubrication performance of floating ring bearings. The results showed that the flow rate obviously affects the bearing area of inside and outside oil film, and the oil-film ratio coefficient inside the bearing. When the oil supply is lower than 10 mL/min, the floating ring bearing is in a serious starved-lubrication state, and the oil-film area of bearing is reduced by 30%. The favorable oil supply flow rate can obviously improve the lubrication conditions, and also can predict the starved state of inner oil-film. Our study provides a theoretical basis for the fault detection of floating ring bearing. • Studied the mechanism of oil-starved lubrication on floating ring bearing. • Established model of oil-starved lubrication to calculate lubrication characteristics for floating ring bearing. • Calculated lubrication characteristics under different lubrication conditions. • Analyzed the influence of oil supply on bearing lubrication characteristics. [ABSTRACT FROM AUTHOR]