20,803 research outputs found
Security of a biometric identity-based encryption scheme
Biometric identity-based encryption (Bio-IBE) is a kind of fuzzy
identity-based encryption (fuzzy IBE) where a ciphertext encrypted under an
identity w' can be decrypted using a secret key corresponding to the identity w
which is close to w' as measured by some metric. Recently, Yang et al. proposed
a constant-size Bio-IBE scheme and proved that it is secure against adaptive
chosen-ciphertext attack (CCA2) in the random oracle model. Unfortunately, in
this paper, we will show that their Bio-IBE scheme is even not chosen-plaintext
secure. Specifically, user w using his secret key is able to decrypt any
ciphertext encrypted under an identity w' even though w is not close to w'.Comment: Journal version of the paper will be appearing in International
Journal of Network Securit
PS-TRUST: Provably Secure Solution for Truthful Double Spectrum Auctions
Truthful spectrum auctions have been extensively studied in recent years.
Truthfulness makes bidders bid their true valuations, simplifying greatly the
analysis of auctions. However, revealing one's true valuation causes severe
privacy disclosure to the auctioneer and other bidders. To make things worse,
previous work on secure spectrum auctions does not provide adequate security.
In this paper, based on TRUST, we propose PS-TRUST, a provably secure solution
for truthful double spectrum auctions. Besides maintaining the properties of
truthfulness and special spectrum reuse of TRUST, PS-TRUST achieves provable
security against semi-honest adversaries in the sense of cryptography.
Specifically, PS-TRUST reveals nothing about the bids to anyone in the auction,
except the auction result. To the best of our knowledge, PS-TRUST is the first
provably secure solution for spectrum auctions. Furthermore, experimental
results show that the computation and communication overhead of PS-TRUST is
modest, and its practical applications are feasible.Comment: 9 pages, 4 figures, submitted to Infocom 201
Force analysis of an open TBM gripping–thrusting–regripping mechanism
This paper presents an approach for the force analysis of an open TBM gripping–thrusting–regripping mechanism, which is a special parallel mechanism driven by hydraulic actuators and constrained by rocky surroundings. The static equilibrium equations of the cutterhead–mainbeam–saddle subassembly are formulated first by exploring the reaction forces in the cross pin situated between the saddle and the gripper cylinder. This is followed by formulating the static equilibrium equations of the inner closed loops formed by the above subassembly, the torque, and gripper cylinders. Consequently, the linear map between the externally applied wrench imposed on the shield and the equivalent thrust forces of the cylinders is developed. The functionality of the force model developed is twofold, i.e., it can be used either to estimate the thrust forces of the cylinders required to resist against the tunneling loads, or to predict the tunneling loads using the measured thrust forces of these cylinders, thus providing important theoretical basis for the design and control of the mechanism
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