What is OpenPGP

This chapter presents a novel access control mechanism for sensitive information which requires permission from different entities or persons to be accessed. The mechanism consists of a file structure and a protocol which extend the features of the OpenPGP Message Format standard by using secret sharing techniques. Several authors are allowed to work in the same file, while access is blocked for not authorized users. Access control rules can be set indicating the minimum number of authors that need to be gathered together in order to open the file. Furthermore, these rules can be different for each section of the document, allowing collaborative work. Non-repudiation and authentication are achieved by means of a shared signature. The scheme’s features are best appreciated when using it in a mobile scenario. Deployment in such an environment is easy and straight.