标准模型中非交互抗选择密文攻击门限密码方案

提出两个抗选择密文攻击的门限密码系统.第一个方案的密文由应用Canetti-Halevi-Kazt的方法到Boneh-Boyen的基于身份加密而得到.第二个方案中的密文与Waters的基于身份加密的密文基本相同,唯一的区别是这里的"身份"是密文的前两部分的hash值.由于服务器在提供解密碎片之前可以公开验证密文的合法性,而合成者又可以公开验证解密碎片的合法性,使我们的两个方案都具有非交互性.二者的安全性都在标准的决定性双线性Diffie-Hellman假设下被证明.

Non-interactive Threshold Cryptosystems Secure Against Chosen Ciphertext Attacks in the Standard Model

Two threshold cryptosystems secure against chosen ciphertext attacks are proposed.The ciphertext in the first system is the resulting of applying the Canetti-Halevi-Kazt approach to the Boneh-Boyen Identity-Based Encryption scheme.While,in the second system,the ciphertext is essentially the same as that in the Waters IBE scheme except that the"identity"here is the hash of the first two parts of the ciphertext.Since the servers can publicly verify the ciphertext validity before providing the decryption shares and the shares can be publicly verified by the combiner,both the schemes achieve the non interactivity.The security in both the proposals is proved under the standard Decisional Bilinear Diffie-Hellman assumption.