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The previous identity-based homomorphic encryption schemes from lattice was analyzed.That the high complexity in previous schemes was mainly caused by trapdoor generation and preimage sampling was pointed out.A new solution was proposed.A novel identity-based encryption scheme from lattice by combining new trapdoor function and dual-LWE algorithm organically was constructed,and it was transformed to an identity-based fully homomorphic encryption scheme from lattice by employing the idea of eigenvector.Comparative analysis shows that the scheme’s complexity of trapdoor generation has a significant reduction,the complexity of preimage sampling has a nearly three-fold reduction,and the SIVP approximation factor has a times reduction.The security of the proposed scheme strictly reduces to the hardness of decisional learning with errors problem in the standard model. 相似文献
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现有的可公开验证的匿名基于身份的加密(Identity-Based Encryption,IBE)机制声称解决了在静态困难性假设之上构造紧的选择密文安全的IBE机制的困难性问题.然而,本文发现,由于该机制的密文不具备防扩展性,使得任何敌手可基于已知的有效密文生成任意消息的合法加密密文,导致该机制无法满足其所声称的选择密文安全性.我们根据不同的密文相等判定条件分别提出两种方法对原始方案的安全性进行了分析,同时在分析基础上指出原始安全性证明过程中所存在的不足. 相似文献
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门限签名能够分散签名权力,比普通单人签名具有更高的安全性。目前大多数门限签名方案都存在密钥托管的问题。针对一种新的基于身份的门限签名方案存在的安全性问题,利用椭圆曲线上的双线性对,文中提出了一个改进的方案。新方案由私钥生成中心和签名成员合作生成密钥,由此防止了PKG伪造签名,较好地解决了密钥托管的问题。在标准模型下对该方案进行了安全性证明,表明该方案是不可伪造的和健壮的。与已有的门限签名方案相比,安全性有较大的提高,效率没有明显的降低。 相似文献
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本文利用椭圆曲线上的双线性对提出一个新的基于身份的多重签密方案,解决以前的传统证书式多重签密方案的证书管理,传递等繁琐问题.并进行了安全性分析,在BDH问题是困难的假设下方案是安全的.签密能够在一个逻辑步骤内同时完成保密和认证两项功能,而其计算量和通信成本都要低于传统的“先签名后加密”,在电子商务等方向有很好的应用前景。 相似文献
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In this paper, we show how to use the dual techniques in the subgroups to give a secure identitybased broadcast encryption(IBBE) scheme with constant-size ciphertexts. Our scheme achieves the full security (adaptive security) under three static (i.e. non q-based) assumptions. It is worth noting that only recently Waters gives a short ciphertext broadcast encryption system that is even adaptively secure under the simple assumptions. One feature of our methodology is that it is relatively simple to leverage our techniques to get adaptive security. 相似文献
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