Recent years have witnessed the trend of leveraging cloud-based services for large scale content storage, processing, and distribution. Security and privacy are among top concerns for the public cloud environments. Towards end-to-end content security, we propose and implement CloudSeal, a scheme for securely sharing and distributing content via the public cloud. CloudSeal ensures the confidentiality of content in the public cloud environments with flexible access control policies for subscribers and efficient content distribution via content delivery network.

Malicious software typically resides stealthily on a user's computer and interacts with the user's computing resources. Our goal in this work is to improve the trustworthiness of a host and its system data. Specifically, we provide a new mechanism that ensures the correct origin or provenance of critical system information and prevents adversaries from utilizing host resources. We define data-provenance integrity as the security property stating that the source where a piece of data is generated cannot be spoofed or tampered with. We describe a cryptographic provenance verification approach for ensuring system properties and system-data integrity at kernel-level. Its two concrete applications are demonstrated in the keystroke integrity verification and malicious traffic detection. Specifically, we first design and implement an efficient cryptographic protocol that enforces keystroke integrity by utilizing on-chip Trusted Computing Platform (TPM). The protocol prevents the forgery of fake key events by malware under reasonable assumptions. Then, we demonstrate our provenance verification approach by realizing a lightweight framework for restricting outbound malware traffic. This traffic-monitoring framework helps identify network activities of stealthy malware, and lends itself to a powerful personal firewall for examining all outbound traffic of a host that cannot be bypassed.

Trust and security have been considered as built-in properties for future Internet architecture. Leveraging the concept of named content in recently proposed information centric network, we propose a name-based trust and security protection mechanism. Our scheme is built with identity-based cryptography (IBC), where the identity of a user or device can act as a public key string. Uniquely, in named content network such as content-centric network (CCN), a content name or its prefixes can be used as public identities, with which content integrity and authenticity can be achieved with IBC algorithms. The trust of a content is seamlessly integrated with the verification of the content's integrity and authenticity with its name or prefix, instead of the public key certificate of its publisher. In addition, flexible confidentiality protection is enabled between content publishers and consumers. For scalable deployment purpose, we further propose to use a hybrid scheme combined with traditional public-key infrastructure (PKI) and IBC. We have implemented this scheme with CCNx open source project on Android.

Trust model is an effort to guarantee secure and high quality interactions in P2P(peer-to-peer) file sharing systems. Traditional trust models always depend on past performance quantified in term of reputation or recommendation. This paper presents PerformTrust -a history and current performance based trust supporting framework which includes an intensive trust model for offering trustworthiness of peers quantitatively and comparatively based on a history performance feedback system and a current performance evaluating system with a decentralized implementation over a structured P2P network. PerformTrust has two main features. First, we introduce a virtual domain in every peer that would take responsible of collecting information about current performance of peers, including files integrity and peers response time. Second, PerformTrust considers both history and current performance of a peer for evaluating trustworthiness. Other contributions include adjustment scenario of the trust model, and a set of experiment that show the effectiveness and benefit of our approach.