Kraus is best known for her work in quantum information and especially in entanglement theory. Together with her coworkers she developed criteria to decide whether a quantum state is separable or entangled and showed how to construct optimal entanglement witnesses and studied the creation of entanglement by unitary quantum gates and dissipative processes. In 2010 she showed how to decide whether two pure quantum states of a many-particle system are equivalent to each other in terms of entanglement. More recently she introduced the notion of "maximally entangled sets" as a new concept generalizing maximally entangled states to the case of considering entanglement between more than two systems (multipartite entanglement). In the field of quantum cryptography, she studied the security of key-distribution protocols and the achievable secret-key rates. Among other results, she and her collaborators Renato Renner and Nicolas Gisin gave an influential information-theoretic security proof for the security of a quantum key distribution protocol