CT-ISG: Real Time Cryptography

安全在许多现代计算机应用中是至关重要的，如电子支付、个性化新闻广播、位置感知电子服务、社交网络中个人信息的自动共享和交换等。密码学提供了许多技术工具，可用于实现安全和隐私目标，但需要大量的计算成本。传统上，这种成本是根据加密协议执行期间交换的消息的数量和大小来衡量的。然而，这种传统的效率度量并不能代表最终用户所感知的性能：最终用户感兴趣的主要效率度量是实时，即，从用户发出请求到请求被服务的时刻所经过的时钟时间。对于在Internet等异构网络上运行的应用程序尤其如此，在这种情况下，延迟和带宽在网络中和时间上都可能发生很大变化。该项目研究了实时模型中加密协议的设计和分析，主要有两个目标：(1)设计在实际时间复杂度度量方面有效的加密协议，如最终用户所感知的，以及(2)利用时间本身作为实现安全目标的工具。例如，本地时间约束（例如，延迟和超时）可用于对全局执行环境中事件发生的顺序实施限制。时间还可以用于引入不同方的能力之间的不对称性，类似于使用昂贵的公钥加密操作通常实现的不对称性。最后，与信息相关的价值通常随时间而变化：今天是有价值的机密信息，明天可能就会公开。本项目将研究实时加密协议设计的所有这些不同方面，首先关注零知识证明系统（一种具有代表性且非常有用的加密协议类别），然后，在开发了适当的定时加密协议执行模型之后，将我们的研究扩展到更大的应用类别。更广泛的意义：安全在许多现代计算机应用中至关重要，并确保公众对网络基础设施的信心。密码学已经开发了许多用于保护电子交易的工具，但是仍然有许多密码学协议在实践中很少使用，因为它们太复杂或计算成本太高。该项目研究利用定时操作以降低计算成本实现安全目标的加密协议，并根据与最终用户体验的效率直接相关的度量。因此，该项目将有助于使密码学在实践中更可用和更广泛地使用。

Security is of primary importance in many modern computer applications, like electronic payments, personalized news broadcasts, location aware electronic services, automatic sharing and exchange of personal information for social networking, etc. Cryptography provides many technical tools that can be used to achieve security and privacy goals, but at a substantial computational cost. Traditionally, this cost has been measured in terms of the number and size of messages exchanged during the cryptographic protocol execution. However, such traditional efficiency measures are not representative of performance as perceived by the final user: the main efficiency measure of interest to the end user is real time, i.e., the amount of clock time elapsed since the user issues a request, till the moment the request is served. This is especially true for applications that run over an heterogeneous network like the Internet, where latency and bandwidth can substantially vary both across the network and over time. This project investigates the design and analysis of cryptographic protocols in a real time model, with two main objectives: (1) designing cryptographic protocols that are efficient with respect to realistic time complexity measures, as perceived by the end user, and (2) exploiting time itself as a tool to achieve security goals. For example, local timing constraints (e.g., delays and time-outs) can be used to enforce restrictions on the order in which events take place in a global execution environment. Time can also be used to introduce asymmetries between the capabilities of different parties similar to what is typically achieved using expensive public key cryptographic operations. Finally, the value associated to information usually varies with time: what is valuable confidential information today, may be publicly available tomorrow. This project will investigates all these different aspects of real time cryptographic protocol design, first focusing on zero-knowledge proof systems (a representative and very useful class of cryptographic protocols), and then, after appropriate models for timed cryptographic protocol execution have been developed, expanding our study to larger classes of applications.Broader significance: Security is essential in many modern computer applications, and to ensure public confidence in the cyber infrastructure. Cryptography has developed many tools that can be used to secure electronic transactions, but still many cryptographic protocols are seldom used in practice because they are too complex or computationally expensive. This project investigates cryptographic protocols that make use of timed operations to achieve security goals at a reduced computational cost, and according to a metric directly related to efficiency as experienced by the end user. As such, the project will help making cryptography more usable and more used in practice.