In this paper, we present a new method of digital steganography, entitled spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. Following a discussion of steganographic communication theory and review of existing techniques, the new method, SSIS, is introduced. This system hides and recovers a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using appropriate keys without any knowledge of the original image. Image restoration, error-control coding, and techniques similar to spread spectrum are described, and the performance of the system is illustrated. A message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, covert communication, image tamperproofing, authentication, embedded control, and revision tracking.

Frequent app bugs and low tolerance for loss of functionality create an impetus for self-healing smartphone software. We take a step towards this via on-the-fly error detection and automated patching. Specifically, we add failure detection and recovery to Android by detecting crashes and "sealing off" the crashing part of the app to avoid future crashes. In the detection stage, our system dynamically analyzes app execution to detect certain exceptional situations. In the recovery stage, we use bytecode rewriting to alter app behavior as to avoid such situations in the future. When using our implementation, apps can resume operation (albeit with limited functionality) instead of repeatedly crashing. Our approach does not require access to app source code or any system (e.g., kernel-level) modification. Experiments on several real-world, popular Android apps and bugs show that our approach manages to recover the apps from crashes effectively, timely, and without introducing overhead.

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Moving target defenses alter the environment in response to adversarial action and perceived threats. Such defenses are a specific example of a broader class of system management techniques called system agility. In its fullest generality, agility is any reasoned modification to a system or environment in response to a functional, performance, or security need. This paper details a recently launched 10-year Cyber-Security Collaborative Research Alliance effort focused in-part on the development of a new science of system agility, of which moving target defenses are a central theme. In this context, the consortium seeks to address the questions of when, what, and how to employ changes to improve the security of an environment, as well as consider how to measure and weigh the effectiveness of different approaches to agility. We discuss several fundamental challenges in developing and using MTD maneuvers, and outline several broad classes of mechanisms that can be used to implement them. We conclude by detailing specific MTD mechanisms used to adaptively quarantine vulnerable code in Android applications, and consider ways of comparing cost and payout of its use.