Efficient Simultaneous Contract Signing

Simultaneous contract signing is a two-party cryptographic protocol: two mutually suspicious parties wish to exchange signatures on a contract. We propose novel and efficient protocol for contract signing based on a construction by Even, Goldreich, and Lempel. We focus on the reduction of on-line computational complexity of the protocol. A significant part of the most time-consuming operations can be pre-computed. An important component used in our protocol is an efficient oblivious transfer, which can be of interest per se.