Computational Collapse of Quantum State with Application to Oblivious Transfer”, full version of this paper, BRICS report nr. RS-03-37, available at www.brics.dk/RS/03/37

Abstract. Quantum 2-party cryptography differs from its classical counterpart in at least one important way: Given blak-box access to a perfect commitment scheme there exists a secure 1−2 quantum oblivious transfer. This reduction proposed by Crépeau and Kilian was proved se-cure against any receiver by Yao, in the case where perfect commitments are used. However, quantum commitments would normally be based on computational assumptions. A natural question therefore arises: What happens to the security of the above reduction when computationally secure commitments are used instead of perfect ones? In this paper, we address the security of 1−2 QOT when computationally binding string commitments are available. In particular, we analyse the security of a primitive called Quantum Measurement Commitment when it is constructed from unconditionally concealing but computationally binding commitments. As measuring a quantum state induces an irre-versible collapse, we describe a QMC as an instance of “computationa