A Study Of Key-Policy Weighted Attribute Based Encryption

In order to satisfy the demand of various new applications of distributed network environment, a new kind of encryption mechanism that can support many-to-many communications of style is necessary, which can replace the traditional one-to-one encryption mechanism. In this way, amount of data can be convenient for storage and transmission in distributed network environment. Attribute-Based Encryption(ABE) comes into being in this situation. ABE mechanism can be divided into Key-Policy Attribute-Based Encryption(KP-ABE) and Ciphertext-Policy Attribute-Based Encryption(CP-ABE).ABE can be regarded as an IBE mechanism which embeds the access structure into. Compared to IBE, the attribute set is thought as a user's identity information, which is not a simple or single information again. In ABE, for sender, who encrypts the message according to some policy and there is no need for it to know which one can decrypt the message. For receiver, if and only if the attributes it has can satisfy the required conditions, it can make the message decrypted correctly. If so, many-to-many communications can be successfully proceeded in the open and un-safe network environment.The paper firstly introduces the recent study of ABE mechanism and gives a description of the basic knowledge and backgrounds which relate with the paper. Then the paper introduces successively the Fuzzy Identity Based Encryption(FIBE),KP-ABE and CP-ABE which relates with this paper, and then gives a detailed description of KP-ABE. In the previous mechanisms, there is almost no research about the importance of attributes. But in real life, attribute and attribute are not always in the same level, that is, the importance of them are not different in the system. And each attribute plays different role in the system. Therefore, attribute should have weight in practice. So in order to have a closer reality, Liu put the weight into CP-ABAE. And because of this, according to the attribute's importance, we give different weights to the corresponding and different attributes. And by this way, the paper proposes a mechanism called Key-Policy Weighted Attributed Based Encryption(KPWABE). Because the KP-WABE scheme can't resist the ciphertext from being tampering, so we adopt some method to realize a KP-WABE scheme which can prevent ciphertext from being tampering. The main work of the paper are as follows:Firstly, according to these attributes' importance in the system, we give each attribute different weights. And, we propose a KP-WABE and prove it secure under the l-th Bilinear Diffie-Hellman Inversion Assumption.Secondly, we improve KP-WABE's scheme, because KP-WABE scheme can't resist the ciphertext from being tampering. The paper uses a hash function to realize a scheme which can prevents the ciphertext from being tampered and we also state the efficiency and security of it.