Specialized anonymous credentials and zero-knowledge proofs

在当今高度互联的世界里，隐私变得越来越重要。不幸的是，今天的电子经济对隐私非常不友好。当我们使用信用卡、借记卡、电子护照或许多其他现代便利设施时，关于我们行为的数据被记录下来，并传播给世界各地的各方，我们几乎无法控制它。匿名凭据系统试图通过允许用户以隐私保护的方式认证和证明关于他们自己的声明来解决这个问题。这是可能的，因为一种称为零知识证明的密码技术，允许一方向另一方证明陈述，而不会透露任何超出证明有效性的额外信息。这是一个非常强大的概念；例如，匿名凭据可以用来构建许多有用的系统，从安全和私有的电子现金系统到医疗记录，这些系统向医疗保健提供者透露的患者信息不会超过患者诊断和治疗所严格需要的信息。 研究文献包含几种通用匿名凭据系统。当与通用的零知识证明系统相结合时，这些方案是非常通用的，并使许多有用的应用在理论上成为可能。不幸的是，使用这些凭据可以获得广泛的证据，但代价是计算和通信的复杂性很高。因此，许多现有的方法对于在例如嵌入式和移动设备上使用来说过于昂贵，从而使得许多潜在的现实世界应用不切实际。然而，通过专注于特殊用途的匿名凭据，通常可以为特定问题设计非常有效的解决方案。 这项工作将集中于扩大目前使用匿名证书系统解决的实际问题集。

In today's highly connected world, privacy is of increasing importance. Unfortunately, today's electronic economy is quite unfriendly to privacy. When we use credit cards, debit cards, e-passports, or many other modern-day conveniences, data about our actions are logged and disseminated to diverse parties around the world and we have little, if any, control over it. Anonymous credential systems attempt to solve this problem by allowing users to authenticate and prove statements about themselves in a privacy-preserving manner. This is possible due to a cryptographic technique known as zero-knowledge proofs, which allow one party to prove statements to another party without revealing any additional information beyond the validity of the proof. This is a very powerful concept; for example, anonymous credentials can be used to build many useful systems ranging from secure and private electronic cash systems to medical records that reveal no more information about a patient to a health care provider than is strictly needed for that patient's diagnosis and treatment. The research literature contains several general-purpose anonymous credential systems. When coupled with general-purpose zero-knowledge proof systems, these schemes are extremely versatile and make many useful applications theoretically possible. Unfortunately, the wide range of proofs that are possible with these credentials comes at the cost of high computational and communication complexity. As a result, many existing approaches are too costly for use on, e.g., embedded and mobile devices, thereby rendering many potential real-world applications impractical. However, by focusing on special-purpose anonymous credentials, it is often possible to design extremely efficient solutions to particular problems. This work will focus on enlarging the set of problems that are currently practical to solve with anonymous credential systems.