ITR/SY(CISE): Cryptography: Examining the Assumptions

密码学是构建信息系统的基本组成部分，随着我们进入全球网络、无处不在的计算设备和电子商务的所谓“信息时代”，我们可以断定密码学将随着时间的推移变得更加重要。该提案旨在通过检查该领域的一些隐含假设来推进密码学的最新技术。可证明安全性的诞生在过去二十年中对该领域的进步做出了重大贡献，使我们能够积累强有力的证据，证明只要攻击者遵守我们正式威胁模型中指定的规则，所考虑的密码系统就可能是安全的。然而，有一个问题是，在实践中，攻击者并不总是按规则行事：只要有机会，他们就会很乐意“作弊”。最近的研究表明，有很多方法可以违背设计师的假设，例如，通过观察模型不允许的时间测量。因此，实际加密设计的目标应该包括找到减少攻击者“作弊”机会的方法，最好是放松我们的假设，充分扩大我们的模型，这样攻击者的行为就会被模型所覆盖。这是我们在这个项目中进行的研究议程。我们建议首先研究实际系统和案例研究如何在实践中违反这些假设。下一步是建立一套实用的对策，可用于加强未来的密码系统抵御这些攻击。最后，我们将寻求新的理论工具、技术和模型来扩展可证明的安全方法，以考虑这些失效模式。如果我们成功的话，这些结果将不仅对密码学的实践，而且对该领域的理论基础做出积极的贡献。

Cryptography is a fundamental building block for building information systems, and as we enter the so-called "information age" of global networks, ubiquitous computing devices, and eletronic commerce, we can expert that cryptography will become only more import with time.This proposal is designed to advance the state of the art in cryptography by examining some of the implicit assumptions that underlie the field. The birth of provable security has contributed significantly to the advances of the field over the past two decades, allowing us to amass strong evidence that-as long as the attacker plays by the rules specified in our formal threat model-the cryptosystem under consideration is likely to be secure. However, one problem is that, in practice, attackers don't always play by the rules: given the opportunity, they will gladly "cheat". Recent research has shown that there are a surprising number of ways to violate the designer's assumptions, for instance by observing timing measurements which the model does not allow for. The goals of practical cryptographic design, then, ought to include finding ways to reduce the opportunity for attackers to "cheat", preferably by relaxing our assumptions and broadening our models enough so that the attacker's behavior cannot help but be covered by the model. This is the research agenda that we take up in this project. We propose first to study real systems and case studies of how these assumptions can be violated in practice. A next step is to build a set of practical countermeasures that can be used to strengthen future cryptosystems against these attacks. Finally, we will seek new theoretical tools, techniques, and models for extending the provable security methodology to take into account these failure modes. If we succeed, these results will make a positive contribution not only to the practice of cryptography but also to the theoretical foundations of the field.