The secure release of identity attributes is a key enabler for electronic business interactions. Users should have the maximum control possible over the release of their identity attributes and should state under which conditions these attributes can be disclosed. Moreover, users should disclose only the identity attributes that are actually required for the transactions at hand. In this paper we present an approach for the controlled release of identity attributes that addresses such requirements. The approach is based on the integration (...) of trust negotiation and minimal credential disclosure techniques. Trust negotiation supports selective and incremental disclosure of identity attributes, while minimal credential disclosure guarantees that only the attributes necessary to complete the on-line interactions are disclosed. (shrink)