A Study Of Hierarchy Attribute-Based Encryption

Attribute-Based Encryption(ABE) is a new type of public key encryption which supports multi-to-multi model. In the Attribute-Based Encryption, identity is not denoted by only one information, and a more flexible access structure is added to this system, and this access structure is consist of several attributes and thresholds. If and only if attributes match access structure, we can get decryption. The most advantage of the system is that sender does not need to know the specific receiver, and receiver who is consistent with the corresponding conditions can decrypt the message from the sender.Attribute-Based Encryption can be divided into two categories: key-policy Attribute-Based Encryption and ciphertext-policy Attribute-Based Encryption, we mainly study key-policy Attribute-Based Encryption in this thesis.Firstly, the thesis introduce the Attribute-Based Encryption, it can divided into four parts:basic Attribute-Based Encryption, key-policy Attribute-Based Encryption,ciphertext-policy Attribute-Based Encryption and hierarchy Attribute-Based Encryption.The thesis detailed description of the four scheme.Secondly, the thesis emphasis introduces the key-policy attribute-based encryption and the hierarchy attribute-based encryption. The advantage of key-policy attribute-based encryption is that add a access structure, this structure can make the access control become more Flexible; and the hierarchy attribute-based encryption solve the high scheme overhead an extensive pairing operations are usually require, improve the efficiency of the algorithm.Because for non-hierarchy attribute-based encryption scheme,during the phase of key generation,one attribute is correspond one sub-key,but for hierarchy attribute-based encryption, only need to own a ancestor node of a lot attributes is OK.Lastly, the thesis put forward a new scheme; this scheme has the follow characteristics:(1) This scheme adds an access structure, this structure is embedded in the key, the key owner can control the structure, and it can make the scheme become more flexible.(2) This scheme is denote the attribute which in the attribute set by tree, each attribute is not a separate entity; some attributes which on the same tree is associate. if x is a node of a attribute tree, then x own all attributes on this tree which it’s deeper than x, so this scheme does not need to paring each attributes. If a user own several attributes which on the same tree with x, but they are deeper than x, the user did not need all the attributes,he only need x is OK, its advantage solve the high scheme overhead an extensive pairing operations are usually require.(3) This thesis proof the scheme is security and analysis its efficiency.