1969年，美国哥伦比亚大学的教授S.Wiesner第一次提出可以将量子力学中的某些特性应用于密码学中。1984年，Bennett和Brassard首先将这一概念付诸实践，提出了世界上第一个量子密钥分发协议（QKD）——BB84协议。自此，各种利用量子力学特性的通信协议不断涌现出来，譬如量子密钥分方法协议（QKD）、量子私人签名、量子直接通信协议（QSDC）、量子隐态传输等等。作为量子信息学中最早的一个研究领域，自今为止，量子密钥分发已经有了长足的发展。借助这些协议，攻击者Eve一旦对量子信道中的粒子进行截取、测量、重发送，都会被合法用户第一时间发现。然而，如果Eve只是对量子信道进行监听，而不对通过量子信道中的粒子做任何操作，那么Eve是不会被通信双方发现的。因此，Eve可以获得整个协议中粒子的个数，再根据粒子与密钥的对应关系，最终获得密钥的长度。随着量子计算的发展及应用，量子密钥长度的安全性将对破译密文产生极大的影响。因此，为了解决密钥长度被泄露的安全隐患，我们在这篇文章中将提出一种新的密钥分发协议。在这个新的协议中，密钥的发送方首先将传送一个N-qubit的量子序列给接收方，其中每个粒子随机的代表1-bit、2-bit、3-bit、4-bit的经典信息。然后，密钥的发送方再传递一个粒子序列，向接收方解释如何对第一个序列中的粒子进行解码。与量子密钥分发类似，量子拍卖也是量子信息中一个研究热点。在量子暗拍中，每一个投标者秘密地将投标价发送给拍卖方，最终，出价最高的投标者将获胜。近几年，赵志文在Naseri文章《the secure quantum sealed-bid auction》的基础上，提出了一种“后验量子暗拍协议”。然而在该协议中，如果存在一个合谋小组，他们可以通过一种攻击方法获取其他合法投标者的出价，从而给拍卖带来安全隐患。He，L.B等人在指出问题的的同时，提出了一种改进协议，但是不幸的是改进后的协议，仍然存在这个问题。在本文中，我们将提出一种加强的量子后验暗拍协议，该协议能够完美地解决以上的问题。

In 1969, S.Wiesner from Columbia University raised, for the first time, that information can be kept secretly due to characteristics of quantum mechanics, the thought Bennett and Brassard were the first ones to put into practice in 1984. They presented protocol BB84, the first quantum key distribution protocol in the whole world. Since then, some protocols based on characteristics of quantum mechanics have appeared, such as quantum key distribution (QKD), quantum private comparison, quantum secure direct communication (QSDC), quantum teleportation, and so on.As one of the earliest areas in the research of quantum information, the quantum key distribution has already been taken a solid step forward. With these protocols, legal users are able to discover an attacker Eve in time while the Eve is intercepting, measuring or retransferring particles in the quantum channel. However, if Eve does nothing but only collects particles during the course of data transmission, the attacker can get the information of how many particles communicators have transferred, through which Eve can acquire N, the length of secret key, with the improvement and application of quantum computing, the security of the secret key length plays an important role for a deciphering message. In this paper, putting the security performance into consideration for a secure quantum communication, a new scheme of quantum key distribution is proposed in order to overcome the defect mentioned above. In the new scheme, two communicators should firstly transfer a particle sequence with N-bit where every particle randomly stands for one of the four coding solutions (one bit, two bits, three bits, or four bits). Secondly, the two communicators send another particle sequence to explain the coding rule of particles. At last, the receiver will decode the first sequence according to the second sequence.Just like quantum key distribution, quantum sealed-bid auction also has been become a hot research topic since the protocol is presented. In the protocol of quantum sealed-bid auction, the bidders must submit their bids to the auctioneer secretly, then the highest bidder will be the winner. Recently, on the basis of the secure quantum sealed-bid auction, Zhao et al. presented the secure quantum sealed-bid auction with post-confirmation. However, if a group of malicious bidders collude with each other, they can conclude the bidding of an honest bidder with a very high probability. So, He et al. presented an improved scheme. They pointed out the loophole existing in Zhao et al.’s protocol, but unfortunately the improved protocol also exists the same loophole as Zhao’s protocol. In this paper, an enhanced secure quantum sealed-bid auction with post-confirmation is proposed. This protocol can solve the problem that a group of malicious bidders collude with each other to obtain the bidding of a bidder.