Collapse-Binding Quantum Commitments Without Random Oracles

We construct collapse-binding commitments in the standard model. Collapse-binding commitments were introduced by Unruh (Eurocrypt 2016) to model the computational-binding property of commitments against quantum adversaries, but only constructions in the random oracle model were known. Furthermore, we show that collapse-binding commitments imply selected other security definitions for quantum commitments, answering an open question by Unruh (Eurocrypt 2016).