  The realm of this thesis is cryptographic protocol theory in the quantum
world. We study the security of quantum and classical protocols against
adversaries that are assumed to exploit quantum effects to their advantage.
Security in the quantum world means that quantum computation does not
jeopardize the assumption, underlying the protocol construction. But moreover,
we encounter additional setbacks in the security proofs, which are mostly due
to the fact that some well-known classical proof techniques are forbidden by
certain properties of a quantum environment. Interestingly, we can exploit some
of the very same properties to the benefit of quantum cryptography. Thus, this
work lies right at the heart of the conflict between highly potential effects
but likewise rather demanding conditions in the quantum world.
