| The Internet and the Internet of things technology not only facilitate communication around the world,but also contain potential information security problems.Today,major countries have elevated cybersecurity to a national strategy.Most of the current cryptosystems are designed based on computational complexity,and their security is increasingly threatened by the rapid development of computer science,especially from the quantum computer.Quantum cryptography is based on the basic principles of quantum mechanics and has unconditional security in theory.This paper starts with the classical digital signature,expounds the reasons why the classical cryptography based on computational complexity is vulnerable to the threat of quantum computer,and then leads to the quantum digital signature.Several premises of the early quantum digital signature protocol are difficult to be satisfied experimentally,which limits the development of quantum digital signature.Researchers continue to improve the original quantum digital signature protocol and experimental conditions,so that the protocol premise can be consistent with the actual experimental conditions.Most quantum digital signature protocols and experiments are about how to achieve theoretically unconditional secure signature of a single bit.If just using a simply iteration way to sign multiple bits,although every bit maintains theoretically unconditional secure,but the overall semantic may be tampered,because an attacker can not tamper with any bit and the corresponding signature but do something based these bits and signatures,to forge a multi-bit message and corresponding signatures which can pass verification.In order to solve this problem,researchers propose a method that first encode the message and then sign it.Although this method can effectively solve the possible vulnerability of quantum digital signature protocol when used to sign multi-bit messages,but it decreases at least half of the signature efficiency.In the process of research,we found this problem and proposed an efficient coding method,and proved that the theoretically unconditional security of multi-bit quantum digital signature can still be satisfied.When signing a 128-bit message,the signature efficiency of our new scheme is 36.92%higher than that of the previous best scheme.During the research period,I completed an experiment using high-speed quantum digital signature together with my collaborators,and the system repetition frequency reached the GHz level.At 125km transimission distance,with the condition that a failure probability less than 10-10,the signature rate still can reach 0.044 bits per second.This paper mainly focuses on the topic of practical quantum digital signature,and summarizes my research achievements in this direction,including the proposal of efficient multi-bit quantum digital signature scheme,high-speed quantum digital signature experiment by using the new interference ring,and parameter optimization of practical quantum digital signature system. |
