Object Protection in Distributed Systems

Withreferencetoadistributedsystemconsistingofnodesconnectedbyalocalareanetwork,we consider a salient aspect of the protection problem, the representation of access permissions and protection domains. We present a model of a protection system supporting typed objects. Possession of an access permission for a given object is certified by possession of an object pointer including the specification of a set of access rights. We associate an encryption key with each object and a password with each domain. Object pointers are stored in memory in a ciphertext form obtained by using the object key and including the value of the domain password. Each process is executed in a domain and can take advantage of a given object pointer only if this object pointer was encrypted by including the password of this domain. A set of protection primitives makes it possible to use object pointers for object reference and to control the movements of the objects across the network. The resulting protection environment is evaluated from a number of salient viewpoints, including ease of access right distribution and revocation, interprocess interaction and cooperation, protection against fraudulent actions of access right manipulation and stealing, storage overhead, and network traffic

Protected pointers to specify access privileges in distributed systems

With reference to a distributed environment consisting of nodes connected in an arbitrary network topology, we propose the organization of a protection system in which a set of subjects, e.g. processes, generates access attempts to memory segments. One or more primary passwords are associated with each node. An access to a given segment can be accomplished successfully only if the subject attempting the access holds an access privilege, certified by possession of a valid protected pointer (p-pointer) referencing that segment. Each p-pointer includes a local password; the p-pointer is valid if the local password descends from a primary password by application of a universally known, parametric one-way generation function. A set of protection primitives makes it possible to manage the primary passwords, to reduce p-pointers to include less access rights, to allocate new segments, to delete existing segments, to read the segment contents and to overwrite these contents. The resulting protection environment is evaluated from a number of viewpoints, which include p-pointer forging and revocation, the network traffic generated by the execution of the protection primitives, the memory requirements for p-pointer storage, security, and the relation of our work to previous work. An indication of the flexibility of the p-pointer concept is given by applying p-pointers to the solution of a variety of protection problems