Abstract: Oblivious transfer is a primitive of cryptography．Endowing a public key system with oblivious transfer function has important practical significance．This paper used the elliptic curve cryptosystems to design two k out of n obli-vious transfer schemes．These schemes can make full use of the property of public key cryptosystems,and do not need to establish a authentication channel in advance．Based on efficient elliptic curve cryptosystems,these schemes are very efficient．The first scheme is directly constructed from the encryption and decryption property of elliptic curve cryptosystems,and the second improves the first．It keeps the advantages of the first and reduces the overhead cost of the first．Elliptic curve cryptosystem is probabilistic,and oblivious transfer based on it can expand the application of oblivious transfer．The new protocol can protect the privacy of both the receiver and the sender．The new protocols also can prevent impersonation attacks,replay attacks and man-in-the-middle attacks．They can be used in an insecure channel.

Key words: Oblivious transfer,Elliptic curve,Public key cryptosystems,Efficient,Privacy,Secure