The Research Of Key-policy Attribute-Based Encryption

Since the21st century, with the development and application of cloud computing,the traditional public key encryption which belongs to one-to-one communicationmodel has been unable to satisfy the need of sharing and processing data safely andconfidentially in distributed network. So the research of support multi-to-multiencryption mechanism has become an inevitable trend. Attribute based encryption is anew type of public key encryption which supports multi-to-multi model. When thesender encrypts the message, he doesn’t need to know the specific that who candecrypt the message, and the receiver only who meets the corresponding conditionscan decrypt the message.This thesis firstly summarizes the relevant research of ABE in recent years，anddetails the KP-ABE scheme which is proposed by Goyal et.al. After careful analysis ofthe paper, we improve the scheme in the following two aspects:First, Goyal’s scheme cannot resist ciphertexts tamper attack，This thesis uses ahash function for verifying validity of the ciphertexts and destroying the malleabilityso as to resist ciphertexts tamper attack.What’s more, for ABE’s key abuse, this paper puts the user’s privacy informationinto the private key and lets it participate in decryption. The authority can trace whohas leaked out his own private key, and then chase the responsibility. So it is a newKP-ABE scheme which could defend against key abuse attacks.