Patent ID: 8290154

Claim:
A method of key generation performed by an apparatus based on a hierarchical identity based encryption scheme, comprising: generating, by a processor of the apparatus, a public parameter and a primary key through an initializing method of the encryption scheme, wherein the primary key is based on a first random number; with respect to each of leaf nodes in a binary tree where subscriber identities are represented by the leaf nodes in the same level, calculating a right key set of a leaf node according to the encryption scheme based on the public parameter, the identity of the leaf node and a right primary key obtained by replacing the first random number with a second random number, the right key set including a right key of the leaf node and right keys of right brother nodes for all the nodes on a path from a root node to the leaf node; and with respect to the leaf nodes, calculating a left key set of the leaf node according to the encryption scheme based on the public parameter, the identity of the leaf node and a left primary key obtained by replacing the first random number with a third random number, the left key set including a left key of the leaf node and left keys of left brother nodes for all the nodes on the path from the root node to the leaf node, wherein the sum of the second random number and the third random number equals to the first random number, and the second random number is different for different subscribers.