| With the rapid development of computer science and the Internet, the network is chosen to be the information transport platform, which has advantages of high efficiency, simple principle and wide spread. People can access the internet to seek information all the time. Meanwhile, people begin to depend more and more on the network which is going to be the primary sources for obtaining information. The network gives us much convenience and efficiency, and also bring so much threat that we cannot ignore. The information security, which is becoming one of the hottest topic, is based largely on cryptography.Identity-based cryptography is an important part of public key cryptosystem. In an Identity-based Encryption Scheme, the public key can be any information of the receivers, such as E-mail address, phone number or other identifiers. The private key can only be generated by a trusted authority, who has the master-key of the cryptosystem.In a threshold encryption system, the secret is dispersed in n receivers. The secret can be recovered when at least t receivers cooperate. Below the threshold t, no information could be leaked. The threshold encryption scheme is constructed for high fault tolerant capability which is more reliable on providing information security.In many threshold encryption systems, it is often required to send more than one massages to different receivers without reconstruction of system. What’s more, the threshold is usually dynamic but not fixed. The traditional threshold encryption schemes have limited flexibility to settle the problem. We propose a new identity-based dynamic threshold encryption scheme. The sender can encrypt a plaintext for dynamic k receivers with threshold t. At least t receivers are needed for decryption. The conceptual model and security notions of our scheme are also fomulized in this paper. Then, we present the analysis of correctness and dynamic performance. Strict proof in IND-sMID-CPA security and IND-sMID-CCA security are given at last. |
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