eb 2 00 4 Unconditionally Secure Quantum m - out - of - n Oblivious Transfer ∗

Quantum cryptography is one example of applying a deep understanding of quantum physics to create a novel technology of potentially enormous significance. Oblivious Transfer (OT) is used as a key component in many applications of cryptography. Crépeau showed the first quantum 1-out-of-2 oblivious transfer in 1994 based on the transmission of polarized light and the exist of secure quantum bit commitment protocol. The protocol he constructed satisfy both the correctness and the privacy for Alice with probability 1 − εn, the privacy for Bob with probability 1 2 . In this paper, we show that quantum can be constructed using only the Bell states, and the scheme satisfies the correctness and the privacy for Alice with probability 1, the privacy for Bob with probability 1 2 . Furthermore, we show the relations between the OTs, i.e. Bit-QOT 2 can be constructed using String-QOT 2 , String-QOT n can be constructed using String-QOT 2 , String-QOTm n can be constructed using String-QOT n , and vice versa. We get the conclusion that String-QOT n can be constructed using Bit-QOT 2 and vice versa. So, String-QOTm n and Bit-QOTm n can be constructed by the Bit-QOT 2 . Finally, We show that quantum bit commitment and quantum coin flipping can be constructed using QOT.