45,966 research outputs found

    On the Feasibility of Fine-Grained TLS Security Configurations in Web Browsers Based on the Requested Domain Name

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    Most modern web browsers today sacrifice optimal TLS security for backward compatibility. They apply coarse-grained TLS configurations that support (by default) legacy versions of the protocol that have known design weaknesses, and weak ciphersuites that provide fewer security guarantees (e.g. non Forward Secrecy), and silently fall back to them if the server selects to. This introduces various risks including downgrade attacks such as the POODLE attack [15] that exploits the browsers silent fallback mechanism to downgrade the protocol version in order to exploit the legacy version flaws. To achieve a better balance between security and backward compatibility, we propose a mechanism for fine-grained TLS configurations in web browsers based on the sensitivity of the domain name in the HTTPS request using a whitelisting technique. That is, the browser enforces optimal TLS configurations for connections going to sensitive domains while enforcing default configurations for the rest of the connections. We demonstrate the feasibility of our proposal by implementing a proof-of-concept as a Firefox browser extension. We envision this mechanism as a built-in security feature in web browsers, e.g. a button similar to the \quotes{Bookmark} button in Firefox browsers and as a standardised HTTP header, to augment browsers security

    Phenomenology from a U(1) gauged hidden sector

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    We consider the phenomenological consequences of a hidden Higgs sector extending the Standard Model (SM), in which the matter content are uncharged under the SM gauge groups. We consider a simple case where the hidden sector is gauged under a U(1) with one Higgs singlet. The only couplings between SM and the hidden sector are through mixings between the neutral gauge bosons of the two respective sectors, and between the Higgs bosons. We find signals testable at the LHC that can reveal the existence and shed light on the nature of such a hidden sector.Comment: 5 pages, 2 figures. Talk given at the Lake Louise Winter Institute 2007, Feb. 19-24, Alberta, Canad

    Testing Realistic Quark Mass Matrices in the Custodial Randall-Sundrum Model with Flavor Changing Top Decays

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    We study quark mass matrices in the Randall-Sundrum (RS) model with bulk symmetry SU(2)L×SU(2)R×U(1)B−LSU(2)_L \times SU(2)_R \times U(1)_{B-L}. The Yukawa couplings are assumed to be within an order of magnitude of each other, and perturbative. We find that quark mass matrices of the symmetrical form proposed by Koide \textit{et. al.} [Y. Koide, H. Nishiura, K. Matsuda, T. Kikuchi and T. Fukuyama, Phys. Rev. D {\bf 66}, 093006 (2002)] can be accommodated in the RS framework with the assumption of hierarchyless Yukawa couplings, but not the hermitian Fritzsch-type mass matrices. General asymmetrical mass matrices are also found which fit well simultaneously with the quark masses and the Cabibbo-Kobayashi-Maskawa matrix. Both left-handed (LH) and right-handed (RH) quark rotation matrices are obtained that allow analysis of flavour changing decay of both LH and RH top quarks. At a warped down scale of 1.65 TeV, the total branching ratio of t \ra Z + jets can be as high as ∼5×10−6\sim 5 \times 10^{-6} for symmetrical mass matrices and ∼2×10−5\sim 2 \times 10^{-5} for asymmetrical ones. This level of signal is within reach of the LHC.Comment: 30 pages, 6 figures. Reference added, typos corrected, discussions in Sec. IV B expanded. Version conforms to the published versio

    A Very Narrow Shadow Extra Z-boson at Colliders

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    We consider the phenomenological consequences of a hidden Higgs sector extending the Standard Model (SM), in which the ``shadow Higgs'' are uncharged under the SM gauge groups. We consider a simple U(1) model with one Higgs singlet. One mechanism which sheds light on the shadow sector is the mixing between the neutral gauge boson of the SM and the additional U(1) gauge group. The mixing happens through the usual mass-mixing and also kinetic-mixing, and is the only way the ``shadow ZZ'' couples to the SM. We study in detail modifications to the electroweak precision tests (EWPTs) that the presence of such a shadow sector would bring, which in turn provide constraints on the kinetic-mixing parameter, sϵs_\epsilon, left free in our model. The shadow ZZ production rate at the LHC and ILC depends on sϵs_\epsilon. We find that observable event rate at both facilities is possible for a reasonable range of sϵs_\epsilon allowed by EWPTs.Comment: 10 pages, 7 figures. Note and refs. adde
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