Research On The Key Isolation Group Signature Scheme

With the rapid development and wide application of information science and technology,the society is gradually informatization.Online shopping,online office,e-commerce and other new things are gradually occupying people's daily life.However,the Internet is not a secure place,there will be violent attacks,hacking,viruses,illegal theft of information and other issues.Therefore,the information security discipline has also become an important research direction in the information age.As one of the main subjects of information security,cryptography uses information encryption,digital signature,identity authentication and key exchange to ensure the security of network communication.As an important field of cryptography,digital signature replaces the traditional seal and handwritten signature.It can identify the signer and ensure the correctness of the transmitted information using the public key cryptosystem and accordingly ensure the integrity,authenticity and non-repudiation of information in the process of receiving and sending.Group signature is a special digital signature with anonymity and traceability.A group member is allowed to sign the message anonymously on behalf of the entire group and the signature can eventually be opened by the group administrator to verify the signer's identity.If a network attack occurs in the process of group signature,key leakage will cause inestimable losses.In order to reduce the harm caused by key leakage,the key self-protection mechanism can be used and guarantee the security of signature by means of forward security,key isolation and intrusion tolerance.This thesis mainly explores the group signature using key-isolation technology and proposes a key-isolated group signature scheme,which further improves the problems of complex structure,long signature length and low signature efficiency of the previous group signature schemes with the property of key self-protection.The scheme uses key-isolation technology to update the key periodically so that the key leakage in one time period will not affect the secure use of the key in other time period.It has both forward security and backward security which can effectively reduces the losses caused by key leakage.At the same time,the properties of bilinear pairings are used in the scheme,which improves the efficiency of group signature to a certain extent.