Jeffery Lotspiech

Traitor tracing for prerecorded and recordable media

In this paper we are focusing on the use of a traitor tracing scheme for distribution models that are based on prerecorded or recordable physical media. When a pirated copy of the protected content is observed, the traitor tracing scheme allows the identification of at least one of the real subscribers who participated in the construction of the pirated copy. We show how we systematically assign the variations to users. We explore under what circumstances traitor tracing technology is applicable for media based distribution and then focus on two challenges specifically related to this form of distribution: We demonstrate a way to encode the variations on the disc that is mostly hidden from the attackers and also remarkably compatible with the existing DVD standard. We also present an efficient key management scheme to significantly reduce the requirement for non-volatile key storage on low-cost CE devices.

Renewable traitor tracing: a trace-revoke-trace system for anonymous attack

In this paper we design renewable traitor tracing scheme for anonymous attack. When pirated copies of some copyrighted content or content decrypting key are found, a traitor tracing scheme could identify at least one of the real users (traitors) who participate in the construction of the pirated content/key. When traitors are identified, the renewable scheme can revoke and exclude the decryption keys used by the traitors during piracy. Moreover, the revocation information included in the newly released content needs not only to disallow traitors to playback the new content, but also provide new tracing information for continuous tracing. This trace-revoke-trace system is the first such system for anonymous attack. It poses new challenges over the trace-revoke system that has extensively studied in the literatures for the pirate decoder attack. We hope the technologies described in this paper can shed new insights on future directions in this area for academia research.

Towards better software tamper resistance

Software protection is an area of active research in which a variety of techniques have been developed to address the issue. Examples of such techniques include code obfuscation, software watermarking, and tamper detection. In this paper we propose a tamper resistance technique which provides both on and offline tamper detection. In our offline approach, the software dynamically detects tampering and causes the program to fail, protecting itself from malicious attacks. Additionally, during program execution an event log is maintained which is transmitted to a clearing house when the program is back online.

Forensic analysis for tamper resistant software

This paper concerns the protection of a software program and/or the content that the program protects. Software piracy and digital media piracy have cost industries billions of dollars each year. The success of the content/software security technologies in a large part depends on the capability of protecting software code against tampering and detecting the attackers who distribute the pirate copies. In this paper, we focus on the attacker detection and forensic analysis. We shall talk about a proactive detection scheme for defeating an on-going attack before the compromise has occurred. We shall also briefly explain another detection scheme for post-compromise attacker identification. In particular, we consider real world scenarios where the application programs connect with their vendors periodically, and where a detection of attacking can bar a hacker user from further business.

Attacks and Forensic Analysis for Multimedia Content Protection

Piracy is one of the biggest concerns in entertainment industry. Digital copies are perfect copies. An anti-piracy defense is to perform forensic analysis and identify who participates in the piracy and disable him/her from doing it again in the future. In this paper, we classify potential pirate attacks in various broadcast type content distribution systems. We shall also present corresponding forensic analysis scheme for those attacks

Practical forensic analysis in advanced access content system

In this paper we focus on the use of a traitor tracing scheme for distribution models that are one-to-many. It can be a networked broadcast system; It can be based on prerecorded or recordable physical media. In this type of system, it is infeasible to mark each copy differently for each receipt. Instead, the system broadcasts limited variations at certain points, and a recipient device has the cryptographic keys that allow it to decrypt only one of the variations at each point. Over time, when unauthorized copies of the protected content are observed, a traitor tracing scheme allows the detection of the devices that have participated in the construction of the pirated copies. The authors have been involved in what we believe is the first large-scale deployment of the tracing traitors approach in a content protection standard for the new generation of high-definition DVD optical discs. Along the way, we have had to solve both practical and theoretical problems that had not been apparent in the literature to date. In this paper we will mainly present this state of practice of the traitor tracing technology and show some of our experience in bringing this important technology to practice.

Flexible traitor tracing for anonymous attacks

Copyrighted materials are divided into multiple segments and each segment has multiple variations that are differently watermarked and encrypted. The combination of watermark and encryption enables one to identify the actual users (traitors) who have engaged in the piracy. In this paper, we shall present a traitor tracing scheme that can efficiently and flexibly defend against anonymous attacks.