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Even though the security of quantum key distribution has been rigorously proven, most practical schemes can be attacked and broken. These attacks make use of imperfections of the physical devices used for their implementation. Since current security proofs assume that the physical devices' exact and complete specification is known, they do not hold for this scenario. The goal of device-independent quantum key distribution is to show security without making any assumptions about the internal working of the devices. In this talk, I will first explain the assumptions 'traditional' security proofs make and why they are problematic. Then, I will discuss how the violation of Bell inequalities can be used to show security even when a large part of the physical devices is untrusted.

We formulate a numerical procedure to calculate Hawking radiation during non-equilibrium black hole formation. The procedure is applied to a static string in thermal AdS and it is shown that for an arbitrary initial state, the final state is an equilibrated heavy quark string. The fluctuations in the quark string are transmitted from the horizon to the boundary leading to Brownian motion in the boundary theory.