2,957 research outputs found
EASYFLOW: Keep Ethereum Away From Overflow
While Ethereum smart contracts enabled a wide range of blockchain
applications, they are extremely vulnerable to different forms of security
attacks. Due to the fact that transactions to smart contracts commonly involve
cryptocurrency transfer, any successful attacks can lead to money loss or even
financial disorder. In this paper, we focus on the overflow attacks in Ethereum
, mainly because they widely rooted in many smart contracts and comparatively
easy to exploit. We have developed EASYFLOW , an overflow detector at Ethereum
Virtual Machine level. The key insight behind EASYFLOW is a taint analysis
based tracking technique to analyze the propagation of involved taints.
Specifically, EASYFLOW can not only divide smart contracts into safe contracts,
manifested overflows, well-protected overflows and potential overflows, but
also automatically generate transactions to trigger potential overflows. In our
preliminary evaluation, EASYFLOW managed to find potentially vulnerable
Ethereum contracts with little runtime overhead.Comment: Proceedings of the 41st International Conference on Software
Engineering: Companion Proceedings. IEEE Press, 201
Mode II Fracture of GFRP Laminates Bonded Interfaces under 4-ENF Test
This experiment studies the mode II fracture behavior of an adhesively bonded joint composed of GFRP laminates. A new beam model is presented to calculate the mode II ERR for GFRP bonded 4-ENF specimens. In this model, the deformation of 4-ENF specimens caused by the relative deflection angle between the upper and lower layers and by the bending deformation of the upper and lower layers, respectively, is introduced; the effect of the adhesive layer deformation is presented. The closed-form analytical solutions of compliance and energy release rate based on the crack compliance method are obtained. The high accuracy of present analytical solutions are verified by finite element analysis through bonded GFRP 4-ENF specimens and compared to the rigid joint model and the CBT model. The interfacial crack propagation is numerically simulated using shear fracture toughness determined in this experiment, from which the predicted critical load results are in good agreement with the experimental results. The conclusion indicates that the compliance and ERR can accurately be predicted using the new bonded 4-ENF beam model
Rigid vortices in MgB2
Magnetic relaxation of high-pressure synthesized MgB bulks with different
thickness is investigated. It is found that the superconducting dia-magnetic
moment depends on time in a logarithmic way; the flux-creep activation energy
decreases linearly with the current density (as expected by Kim-Anderson
model); and the activation energy increases linearly with the thickness of
sample when it is thinner than about 1 mm. These features suggest that the
vortices in the MgB are rather rigid, and the pinning and creep can be well
described by Kim-Anderson model.Comment: Typo corrected & reference adde
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