Catálogo de publicaciones - libros

The latest trend on privacy, is that you go to a work service you feel respects your privacy, then you’re happy and you give them the data.

If there’s some problem with calculating pass codes, according to date of birth, place of birth, I create then I’m happy nobody can actually track me in this way. This is actually like the lost and found office of a railway station, and it’s OK I’m able to receive information.

In pervasive computing environments, trust among parties is lacking. New mechanisms are required in order to build trust without relying on existing relationships. We present a solution to establish trust based on a history of previous interactions among parties. Past interactions can be proven while assuring the untraceability and anonymity of provers.

This talk is about trust establishment with privacy, so I will briefly explain what we mean by trust, what we mean by trust establishment and why privacy is important in such a context.

In this paper we describe Turtle, a peer-to-peer architecture for safe sharing of sensitive data. The truly revolutionary aspect of Turtle rests in its novel way of dealing with trust issues: while existing peer-to-peer architectures with similar aims attempt to build trust relationships on top of the basic, trust-agnostic, peer-to-peer overlay, Turtle takes the opposite approach, and builds its overlay on top of pre-existent trust relationships among its users. This allows both data sender and receiver anonymity, while also protecting intermediate relay in the data query path. Furthermore, its unique trust model allows Turtle to withstand most of the denial of service attacks that plague other peer-to-peer data sharing networks.

Today I will talk about a project which aims at designing a peer-to-peer network for safe and private data sharing. The motivation for this work is a development that threatens to shut down peer-to-peer file sharing networks, and that’s a recent tactic by the recording industry to take legal action against peerto- peer type networks. So first I want talk about the peer-to-peer file sharing phenomenon: in general, its origin, some of the positive social aspects of such a thing, and the tactical attacks that a peer-to-peer network is subject to. I will then focus on a specific attack that motivates our work, namely illegal users being sued, and discuss possible defences. Our solution, which we call Turtle because as you will see, it is slow but safe, cannot reach the performance of general existing file sharing networks, but at the same time we think it does a good job in protecting users against legal harassment.

This note presents a new way of composing cryptographic primitives which makes some novel combinations possible. For example, one can do threshold decryption using standard block ciphers, or using an arbitrary mix of different decryption algorithms – such as any three keys out of two AES keys, a 3DES key, an RSA key and a one-time pad. We also provide a new way to combine different types of primitive, such as encryption and signature. For example, Alice can construct a convertible signature that only Bob can verify, but which he can make world-verifiable using an AES key. We can incorporate even more exotic primitives, such as micropayments and puzzles, into compound constructs.

Previously, there had been two basic ways to combine cryptographic primitives. One could either design a compound primitive, perhaps using the homomorphic properties of discrete exponentiation, or one could embed several primitives into a protocol. Neither is ideal for all applications, and both have been extremely vulnerable to design errors. We provide a third construction that also allows the designer to do new things. We show, for example, how to incorporate cyclic dominance into a cryptographic mechanism, and how it might be used in a digital election scheme. Our new construction not only complements existing ways of composing crypto primitives; it also has the virtue of simplicity.

This talk is about how we go about composing privacy properties. This workshop is about protecting privacy, and authentication and privacy are not only functionally in conflict, they also use different kind of technical mechanisms. Now how do we “compose” cryptographic primitives? I’ve put “compose” in inverted commas because it is also used by the operating system guys to describe a separate bundle of issues. If you can come up with a better slogan for what’s going on here then I would very much like to hear it.

In some instances, it may be possible to protect access to a user’s personal data by authorising the return addresses replies pertinent to that user are being sent to, rather than authenticating the principal making the request. This relationship between a user’s identity and authorised locations can offer a new design dimension when trying to improve privacy protection.

The argument set up by Bruce Christianson and collaborators is that authentication verifying claimed identities and privacy are currently conflicting requirements.

I’d like to talk about emergent properties, something that you are somewhat familiar with from previous research in security, and I’d like to focus on the security aspects of these properties in ad-hoc networks. This work has benefited from discussions with my colleagues, Bill Arbaugh, John Baras and Jonathan Katz at the University of Maryland.