The Security Of Quantum Seal

Date sealing is a cryptographic problem between two parties. A sender (Alice) stores some secret date in a certain form, so that any other reader (Bob) can read it without Alice’s helping. A common example of classical data sealing is closing a latter in an envelope with a wafer of molten, into which was pressed the distinctive seal of the sender. But the basic idea of quantum seal is to use quantum state encoding classical bits. Its goal can be simply described as follows:The owner encodes the sealed secret message from these states without the help of its owner. Meanwhile, if the message has been decoded, it should cause an inevitable disturbance on the states, the action should be detected bv the owner.The main structure of the article is as follows. In chapter1, we introduce the development of cryptography and give some basic knowledge of quantum mechanics which this topic research institute should be. In chapter2, quantum seals are summarized. The definition and model of quantum seal are presented. In chapter3, in view of the perfect quantum seal an attack strategies are put forward. According the characteristic of the sealing style, we discuss some of the other attack situation, all of them are probability success. We define a pair of completeness project operator Po and P1to make a project measure which can successfully decode the sealed message but not detected at all. Further more, aiming at imperfect quantum seal agreement, deduce the relationship between readability and safety of imperfect quantum seal. The relation the readability a and safety β3to meet is:β≤1/2, α+β≤9/8. Finally an example is given to further illustrate the relation.