Verifiable oblivious transfer protocol

The Oblivious Transfer (OT), introduced by Rabin in 1981, has become an important and fundamental cryptography technique. An OT protocol should have two important characteristics: the sender's privacy and the chooser's privacy. The sender is a party who will deliver a secret to the chooser. The chooser is another party who acts as receiver to learn some information about the input from the sender. The chooser learns of certain information concerning the sender's input while the sender is not allowed to know what the chooser has learned. Moreover, the chooser cannot acquire any messages that he/she did not choose. Naor and Pinkas have recently proposed an efficient oblivious transfer protocol (EOT) that implementes 1-out-of-n protocol, but this EOT has a flaw: it cannot withstand "the same message attack." In this paper, we will improve Naor and Pinkas EOT and make it resistant to "the same message attack."