How to construct and manage unconditionally secure ID-based crypto-infrastructures

本研究项目重点研究无条件安全的加密基础设施，它保证了在加密基础设施下颁发的签名或证书的不可伪造性，而不需要任何未经证明的计算假设。通过仔细研究基于公钥加密的数字签名的更成熟的安全概念，并考虑到无条件安全设置中签名方案的理想要求，我们成功地为这种加密基础设施建立了一个健全而强大的概念。我们还揭示了在无条件设置中出现的相关安全概念之间的有趣关系，并且重要的是，证明了我们的新安全概念是迄今为止已知的无条件安全认证和签名方案中最强的。此外，我们证明了我们的安全概念包含了公钥签名方案的安全概念，即自适应选择消息攻击下的存在不可伪造性。最后，我们提出了一种具体的方法来构建和管理这种无条件安全的加密基础设施，以满足我们最强的安全理念。

This research project focuses on the unconditionally secure crypto-infrastructures, which guarantees the unforgeability of signatures or certificates issued under the crypto-infrastructures without any unproven computational assumptions. We successfully established a sound and strong notion for such crypto-infrastructures by carefully examining the more established security notions for digital signatures based on public-key cryptography, and by taking into account desirable requirements of signature schemes in the unconditional security setting. We also revealed an interesting relation among relevant security notions which have appeared in the unconditionally setting, and significantly, proved that our new security notion is the strongest among all those for unconditionally secure authentication and signature schemes known to date. Furthermore, we showed that our security notion encompasses that for public-key signature schemes, namely, existential unforgeability under adaptive chosen-message attack. Finally we proposed a concrete method to construction and manage such unconditionally secure crypto-infrastructures that meet our strongest security notion.