CT-ISG: Crypto Algorithms for an Integrated Approach to Conditional, Revocable and Traceable Anonymity

随着个人活动记录越来越计算机化和相互关联，隐私成为一个更具挑战性的问题。 当合法的安全需求需要能够链接不同的交易，甚至获得有关所涉个人的详细信息时，这尤其具有挑战性。 该项目的重点是实现妥协的加密技术：交易记录应该是匿名的，直到出现特殊情况（例如特定个人的错误行为，或需要采取特殊措施的紧急情况）。 人们希望在交易发生之前详细说明这些情况，这样个人就可以选择不参与没有为他或她提供足够隐私保证的交易。 有条件匿名/有条件披露是指个人用户是匿名的，直到她的活动违反了一定的条件，在这一点上，一些关于她的信息成为已知的。 可撤销的匿名性意味着用户对所有人都是匿名的，但只有在紧急情况下才参与的特殊匿名撤销受托人。 可追踪匿名意味着，在特殊情况下，可以快速跟踪特定用户的所有交易;这可以是一种条件匿名形式，其中情况是由于用户的不当行为或可追踪匿名，其中受托人决定何时运行跟踪算法。 该项目研究了允许个人和组织之间开发和执行匿名合同的技术，这些合同阐明了个人用户在什么情况下可以了解什么。

As records of individuals' activities become increasingly computerized and linked, privacy becomes an ever more challenging problem. It is especially challenging when legitimate security needs require the ability to link different transactions and even obtain details about the individuals involved. The focus of this project is on cryptographic technologies that achieve a compromise: transaction records should be anonymous until special circumstances (such as wrong-doing on the part of a particular individual, or an emergency that requires special measures) arise. One wants to specify these circumstances before a transaction takes place, so an individual can choose not to participate in a transaction that does not provide him or her with sufficient privacy guarantees.The project considers several trade-offs between anonymity and accountability. Conditional anonymity/conditional disclosure means that an individual user is anonymous until her activities violate a certain condition, at which point some piece of information about her becomes known. Revocable anonymity means that a user is anonymous to all but a special anonymity-revoking trustee that only becomes involved in case of emergency. Traceable anonymity means that, under special circumstances, it is possible to quickly trace all of a particular user's transactions; this can be a form of conditional anonymity where the circumstances are due to the user's misbehavior or revocable anonymity where a trustee decides when to run the trace algorithm. This project investigates techniques that allow one to develop and enforce anonymity contracts between individuals and organizations that spell out what can become known about the individual user and under what circumstances.