## 1 Introduction  
Quantum oblivious transfer (QOT) and quantum bit commitment (QBC) protocols are basic in quantum cryptography. They are important building blocks of multi-party secure computations. The study of QOT was started by [PERSON] and [PERSON] [1]. In 1992, a practical QOT protocol was proposed [2]. However, in these two protocols, if [PERSON] measures the pulses after [PERSON] disclosing the basis, he will get both messages and [PERSON]'s privacy will be destroyed. In the light of this drawback, [PERSON] proposed a QOT protocol [3] based on a QBC scheme [4] to ensure that [PERSON] cannot delay his measurement. Then, [PERSON] proved that QOT constructed based on QBC [5] is secure. Shortly afterwards, [PERSON], [PERSON] and [PERSON] separately presented no-go theorem and proved that there is no non-interactive QBC protocol with statistical security [6; 7; 8; 9]. Subsequently, a great number of works that extend the framework of no-go theorem and further prove the impossibility of the standard QBC has been presented since [PERSON], [10; 11; 12; 13; 14; 15; 16]. These results indicate that QOT protocols constructed based on QBC are not secure either. Then, quantum secure computations are also considered to be insecure [17; 18; 19; 20]. Researchers Then, attempt to construct QBC protocols that can evade the no-go theorem. The most famous ones are relativistic QBC protocols, which were first proposed by [PERSON] [21; 22; 23; 24]. The protocol in Ref. [23] was implemented by different groups [25; 26]. The time during commit phase and opening phase is limited by the distance between the trusted agents, which may be a restriction for building other multi-party cryptographic protocols. In addition, some QBC with computational security were proposed. Unconditionally binding and computationally concealing QBC schemes were presented by [PERSON] [27] and [PERSON] [28], respectively, and in 2016, another computationally binding commitment scheme was proposed and it can be realized from hash functions like SHA-3 [29]. The security of these QBC protocols depends on the limited computing power of the adversary. Once the computing power is improved in the future, the security of these protocols are threatened. Several QBC protocols were proposed based on physical hypothesis, such as bounded-quantum-storage model [30; 31], noisy-storage model [32; 33; 34] and technological limitations on non-demolition measurements [35], the security of these protocols is threatened by the development of techniques. Some QBC schemes with security requirements relaxed were put forward, such as cheat-sensitive QBC [36; 37; 38; 39] and game theoretic secure QBC [40]. There are also some non-relativistic QBC schemes which are claimed to be unconditionally secure [41; 42; 43; 44; 45; 46]. However, most of them only exist theoretically. For example, in Ref. [43] Bob stores the quantum registers unmeasured until _opening phase_, which can be hardly implemented in practice. In this paper, we do not devote to evading the no-go theorem. We give the definition of physical security. As long as the physical security is satisfied, even the attacker who ow ownes all the resources of the earth cannot break the protocol. The physical security was first proposed in Ref. [47]. The time complexity of no-go theorem attack algorithm is \(O(2^{3n})\), where \(n\) is the security parameter of the QBC. In addition this algorithm needs at least \(O(2^{2n})\) size of memory space to store the matrix of the unitary transformation. We define that if the entry number of the attack matrix is greater than the total number of protons on the earth (approximately \(10^{50}\)), QBC achieves physical-secure binding. It means when \(n>83\), no-go theorem attack can hardly be realized in practice. Compared with those QBC schemes based on physical hypothesis, the definition of physical security limits the attacker with all the resources of the earth. QBC protocols that achieve physical security are more secure than other protocols based on physical hypothesis.