Hi all,
Next Tuesday's talk will be by Christian Schaffner (CWI) at 5pm in HIT
K51. Title and abstract below.
Roger
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Improving the Security of Quantum Protocols via Commit-and-Open
We consider two-party quantum protocols starting with a transmission of
some random BB84 qubits followed by classical messages. We show a
general "compiler" improving the security of such protocols: if the
original protocol is secure against an "almost honest" adversary, then
the compiled protocol is secure against an arbitrary computationally
bounded (quantum) adversary. The compilation preserves the number of
qubits sent and the number of rounds up to a constant factor. The
compiler also preserves security in the bounded-quantum-storage model
(BQSM), so if the original protocol was BQSM-secure, the compiled
protocol can only be broken by an adversary who has large quantum memory
and large computing power. This is in contrast to known BQSM-secure
protocols, where security breaks down completely if the adversary has
larger quantum memory than expected. We show how our technique can be
applied to quantum identification and oblivious transfer protocols.