Research Of The Key Insulation Mechanism And Blind Signature Of Attribute Based Encryption

With the widely application and development of information technology, thepopularity of the Internet rapidly increases. Internet becomes a indispensableimportant carrier for human production and living, thus the security requirements ofinformation becomes more prominent and complicated. Computer viruses, trojans,security protocol loophole, man-made factors and so on may cause the key exposure,and now key exposure becomes more and more common, and the damage is also moreand more serious, so a large number of researchers invest in the problem of keyexposure to avoid losses and damage caused by the key exposure. Key isolationmechanism, as an important means to solve the problem of key exposure, divides thewhole system period into several time slice, and the user private key is composed oftemporary private key and assist key, temporary private key is stored in the userequipment, and assist key is stored in assist device, user device updates temporaryprivate key through interaction with assist device regularly. assist key is onlyresponsible for updating the temporary private key at the beginning of the time slice,and not participates in cipher decryption operation, so temporary private key exposurein some time slice will not effect the security of temporary private key in other timeslice. Since key isolation mechanism not only guarantees the forward security, butalso guarantees backward safety, key isolation mechanism has caused wide publicconcern in recent years. In addition, blind signature makes the signer not know themessage content during the signature process, and avoids the leakage of requesterprivate information, protecting the privacy of the requester information effectively.In this paper, we firstly analyzed and researched the existing key isolationmechanism and blind signature schemes, then studied the problem of key exposureand signing message without knowing its content in attribute based encryption, finallyacquired following results:(1) In attribute based signcryption scheme, private key exposure not only causesthe threat to the message confidentially, but also greatly damages the messageauthentication. For the problems of key protection, this paper combined attributebased signcryption with key isolation mechanism, and implemented an attribute basedkey insulated signcryption with bidirectional anonymity. The improved schemeretained the original anonymity, at the same time had the characteristics of keyisolation.(2) In attribute based ring signature scheme, if a user uses a subset of his ownattribute set to sign a message, all users possessing the subset constituted a ring in thesystem, any other user can not identify the user in the ring who generates the signature, so key exposure in ring signature threats the security of user himself as well as otherusers in the same ring, so the key protection in ring signature is very importance. Thispaper introduced parallel key isolation mechanism into attribute based ring signature,built a attribute based parallel key isolation ring signature scheme, and finally gavethe safety analysis and demonstration of attribute based parallel key isolation ringsignatur in random model.(3) Blind signature mechanism makes the signer sign a message under thecondition of not knowing the message content, and when the blind signatureisunblindly translated, the signer can not track the result of the last signature. Thispaper introduced blind signature mechanism to attribute based signature scheme, builtattribute based blind signature and partially blind signature. finally, security ofattribute based blind signature in random oracle model was expounded and specified.