**Abstract:** The objective of this work is to introduce the notion of formal security into
quantum computation. In order to achieve this, we introduce a new security model,
containing a quantum communication model. We will lay some stress on formal details
to show which are the problems arising in a formal definition of quantum security.

Based on this model we will analyse some basic aspects of quantum protocols:

- Are quantum protocols composable?
- Do classically secure classical protocols stay secure in a quantum environment?

Both questions we will answer by and large positively. This discussion (and especially the proofs) will be less formal, because of the complex nature of the underlying communication processes.

**Permalink:** http://www.ut.ee/~unruh/publications/unruh02formal.html