The problem of protecting digital content -- software, video, documents, music, etc. -- from illegal redistribution by an authorized user, is the focus of considerable industrial and academic effort. In the absence of special-purpose tamperproof hardware, the problem has no cryptographically secure solution: once a legitimate user has purchased the content, the user, by definition, has access to the material and can therefore capture it and redistribute it. A number of techniques have been suggested or are currently employed to make redistribution either inconvenient or traceable. In this paper we introduce digital signets, a new technique for protecting digital content from illegal redistribution. The work motivates the study of the previously unexamined class of incompressible functions, analysis of which adds a cryptographic twist to communication complexity. 1 Introduction The problem of protecting mass-distributed digital content, such as software, audio, video, and digital libr...

Abstract. We provide a selective survey on software protection, including approaches to software tamper resistance, obfuscation, software diversity, and white-box cryptography. We review the early literature in the area plus recent activities related to trusted platforms, and discuss challenges and future directions. 1