中文摘要：

（t，n）门限认证加密方案允许t个以上签名方产生指定接收方的认证加密签名，使得只有指定的接收方能够恢复消息和验证消息的完整性，而其他人却无法做到这一点．最近，在Tseng和Jan的认证加密方案的基础上，Chung等构造了一个（t，n）门限认证加密方案．该方案运用了分工式签名技术，有效地减轻了签名方的负担．然而，该文作者对该方案的安全性仅进行了解释性说明．目前，文献中没有对分工式门限认证加密的形式化刻画，没有出现可证安全分工式门限认证加密方案．事实上，Chung等的分工式门限认证加密方案存在设计上的缺陷．文中给出了分工式门限认证加密方案的形式化模型和安全模型，基于双线性映射构造了一个新的分工式门限认证加密方案．在随机预言机模型下，证明了该方案对于适应性选择密文攻击是语义安全的，该方案对于适应性选择消息攻击是存在性不可伪造的．方案的安全性可规约到计算性Diffie—Hellman（CDH）困难假设和决定性双线性Diffie—Hellman困难假设（DBDH）．

英文摘要：

A （t,n） threshold authenticated encryption scheme allows t or more signers to generate a signature on a message for the designated recipient. No one except the designated recipient can recover the message and verify the integrity of the message. Based on Tseng and Jan＇s authenticated encryption scheme, Chung et al. recently proposed a （t,n） threshold authenticated encryption scheme by applying a division-of-labor signature to reduce the workload of the signers. However, the authors only gave some intuitional security proof. No published paper analyzes formally division-of-labor based threshold authenticated encryption （DOLTAE） scheme in the literature, let alone any proven-secure scheme. As matter of fact, there exists a design defect in the DOLTAE scheme. In this paper, the authors would like to formalize the DOLTAE scheme and its security model. According to the formal model, the authors present a new DOLTAE scheme from bilinear pairings. On the assumptions of Computational Diffie-Hellman （CDH） and Decisional Bilinear Diffie-Hellman （DBDH）, the proposed scheme has been proved to be tightly semantically secure against adaptive chosen-ciphertext attacks （IND-CCA2） and existential unforgeable with integrity of ciphertext （UF-CTXT） against the adaptive chosen-message attacks in the random oracle model.