基于椭圆曲线公钥系统的不经意传输协议

Oblivious Transfer Based on Elliptic Curve Public Key Cryptosystems

不经意传输是密码学中的基础协议。使公钥系统具有不经意传输功能有重要的实际意义。利用椭圆曲线公钥系统设计了两个k-out-of-n不经意传输协议,协议充分利用公钥系统的优势,不需要预先建立认证通道,同时椭圆曲线公钥系统的高效性使协议具有很高的执行效率。第一个方案直接利用椭圆曲线公钥系统的加密方法和解密方法设计;第二个方案是第一个方案的改进,它保留了原方案的优势,同时降低了执行的开销。椭圆曲线公钥系统的概率加密性可以大大扩展协议的应用范围。两个协议都能够保证发送者和接收者的隐私性,同时能够抵抗冒名攻击、重放攻击以及中间人攻击,因此在不安全的信道传递消息时依然是安全的。

Oblivious transfer is a primitive of cryptography. Endowing a public key system with oblivious transfer func- tion 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 effi- cient. The first scheme is directly constructed from the encryption and decryption property of elliptic curve cryptosys- tems,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 pre- vent impersonation attacks, replay attacks and man-in-the-middle attacks. They can be used in an insecure channel.