A protocol issue for the malicious case of Yao's garbled circuit construction

We present a protocol issue that arises with the use of oblivious transfer in the malicious case of several two-party computation protocols based on Yao’s garbled circuit. We describe this issue for a protocol by Pinkas (Eurocrypt 2003) and for the Fairplay protocol, and we discuss why this issue still persists for a recently suggested modification of the Fairplay protocol. We propose a solution using committed oblivious transfer instead of (plain) oblivious transfer. We also introduce the notion of committing oblivious transfer, which leads to an alternative, potentially more efficient solution. 1