Research on treatment to prevent loss of cryptographic key

我们构造了一个有效的秘密共享方案（SSS）（包括“1-out- n”密码系统），并考虑了对密码密钥丢失的处理。更具体地说，我们提出了混合型P2P网络模型，该模型在系统保留或收集SSS份额的情况下不访问根服务器。该方案在丢失终端设备（如移动PC机）和可移动密钥（如USB密钥）的情况下，仍能保证数据的完整性。我们主要采用以下两种方法来解决上述问题：(1)系统使用工作密钥（而不是主密钥）对移动PC中的数据进行加密；(2)系统使用根服务器的认证码对加密后的数据进行解密。因此，我们的系统实现了与（k, n）阈值方案相关的共享生成和数据恢复。该系统为服务器和客户端机器之间的认证代码提供了数据完整性。从实施的角度来看，盈利绩效评价更是如此。我们还提出了计算椭圆曲线对边的快速软/硬件实现。目前基于配对的密码系统有很多应用，如基于id的密码系统、短签名、广播加密等。然而，配对计算存在一些缺陷。这意味着与传统的计算方法相比，计算配对的工作量非常大。我们提出了一些有效的计算配对算法。其中之一是高效（扭曲）Ate配对的建议。扭曲的Tate配对比传统的Tate配对要快。我们给出了Eta T配对的环缩短技术。这种配对可以应用于twisted Ate配对，在软件实现方面，计算成本降低了25% ~ 50%。此外，我们还证明了当参数rho近似为2时，扭曲Ate对的改进在理论上比Ate对更快。以同样的方式，我们还提出了其他有效的配对，并将其与传统配对进行了比较。少

We construct efficient secret sharing scheme (SSS) (including "1-out-of-n" cryptosystem) and consider the treatment against the loss of cryptographic key. To make more concretely, we propose Hybrid P2P network model which does not access to the root server in case the system preserves or gathers the share of SSS. Our scheme can give some guarantee for the data integrity even when the system loses both terminal machines (e.g. mobile PC) and removable cryptographic key (e.g. USB key). We solve the above problem mainly using the following two methods : (1) The system uses the work key (not master key) to encrypt the data in mobile PC ; (2) The system uses the authentication code from the root server, which decrypts the encrypted data. Consequently, our system realizes the share's generation and the data recovery related to the (k, n) threshold scheme. The system gives the data integrity for the authentication code between server and client machines. Profitable performance evaluation is al … More so obtained from implementation point of view.We also propose fast software/hardware implementation to calculate the paring on elliptic curve. Nowadays there are so many applications in the pairing based cryptosystem, e.g. ID-based cryptosystem, short signature, broadcast encryption, etc. However there exist some drawbacks in pairing calculation. This means that the amount of work to calculate the pairing is very large compared to the conventional calculation method. We propose some efficient pairing algorithms for calculation. One of them is a proposal of an efficient (twisted) Ate pairing. The twisted Ate pairing is faster than the conventional Tate pairing. We give the loop-shorten technique of the Eta T pairing. This pairing can be applied to the twisted Ate pairing and computational cost is reduced by 25 to 50 % in terms of software implementation. In addition, we show that the improvement of the twisted Ate pairing is theoretically faster than the Ate pairing when parameter rho is approximately 2. In the same way, we also proposed other efficient pairings and estimate them compared to conventional pairings. Less