Abstract: One embodiment of the present invention provides a system that authenticates requests between tasks in an operating system. During operation, a first task prepares a request to perform an operation in a second task. In doing so, the first task attaches a credential to the request, and then a trusted entity transfers the request and the credential to the second task. Next, the second task determines whether the credential is valid. If the credential is valid, the second task determines from the credential whether the first task is authorized to request the operation, and, if so, proceeds to perform the operation.

Abstract: One embodiment of the present invention provides a system that controls accesses to revisions of documents in the presence of a multi-user permissions and ownership model. During operation, the system receives a request to on behalf of a user to access a revision of a document. If the request is directed to a most-recent revision of an existing document, the system uses the multi-user permissions and ownership model to control access to the revision. Otherwise, if the request is directed to a previous revision of the document, the system grants access to the revision only if the user was the owner of the document at the time of the revision.

Abstract: One embodiment of the present invention provides a system that controls accesses to revisions of documents in the presence of a multi-user permissions and ownership model. During operation, the system receives a request to on behalf of a user to access a revision of a document. If the request is directed to a most-recent revision of an existing document, the system uses the multi-user permissions and ownership model to control access to the revision. Otherwise, if the request is directed to a previous revision of the document, the system grants access to the revision only if the user was the owner of the document at the time of the revision.