Christopher Portman, Queen's University, Belfast
Abstract:
Cryptography (AC) is a composable security framework by
Maurer and Renner, which generalizes previous frameworks, e.g.,
Canetti's Universal Composability (UC). By defining security on a
level of abstraction where the underlying computational model has not
been specified, it applies seamlessly to both classical and quantum
cryptography. One of the main contributions of AC --- apart from
simplifying the security model --- is that it allows multiple
non-cooperating dishonest players to be directly modeled, e.g.,
coercibility.
This talk will be an introduction to (quantum) AC, with focus on the
novelties of this framework. In particular, I will talk about some
current research with Renato Renner, in which we are defining the
security of device independent protocols by modeling the quantum
devices as dishonest players.
I will use the occasion to dispel two common misconceptions about
composable security. The first is that defining composable security
is complicated; with AC it is actually straightforward. The second is
that using a composable framework leads mostly to impossibility
results. I will explain how, by explicitly modeling the (hidden)
assumptions of stand-alone security, stand-alone protocols can (and
should) be proven secure in a composable framework.