Biblio

User's digital identity information has privacy and security requirements. Privacy requirements include confidentiality of the identity information itself, anonymity of those who verify and consume a user's identity information and unlinkability of online transactions which involve a user's identity. Security requirements include correctness, ownership assurance and prevention of counterfeits of a user's identity information. Such privacy and security requirements, although conflicting, are critical for identity management systems enabling the exchange of users' identity information between different parties during the execution of online transactions. Addressing all such requirements, without a centralized party managing the identity exchange transactions, raises several challenges. This paper presents a decentralized protocol for privacy preserving exchange of users' identity information addressing such challenges. The proposed protocol leverages advances in blockchain and zero knowledge proof technologies, as the main building blocks. We provide prototype implementations of the main building blocks of the protocol and assess its performance and security.

Without violating existing app security enforcement, malicious modules inside apps, such as a library or an external class, can steal private data and abuse sensitive capabilities meant for other modules inside the same apps. These so-called "module-level attacks" are quickly emerging, fueled by the pervasive use of third-party code in apps and the lack of module-level security enforcement on mobile platforms. To systematically thwart the threats, we build CASE, an automatic app patching tool used by app developers to enable module-level security in their apps built for COTS Android devices. During runtime, patched apps enforce developer-supplied security policies that regulate interactions among modules at the granularity of a Java class. Requiring no changes or special support from the Android OS, the enforcement is complete in covering inter-module crossings in apps and is robust against malicious Java and native app modules. We evaluate CASE with 420 popular apps and a set of Android's unit tests. The results show that CASE is fully compatible with the tested apps and incurs an average performance overhead of 4.9%.