Abstract: Methods and apparatus, including computer program products, implementing and using techniques for document authentication. An electronic document is presented to a user. The electronic document has data representing a signed state and a current state. A disallowed difference between the signed state and the current state is detected, based on one or more rules that are associated with the electronic document. A digital signature associated with the electronic document is invalidated in response to the detecting.

Abstract: Methods and apparatus, including computer program products, implementing and using techniques for establishing trust in an electronic document. An electronic document is received. State dependent content in the electronic document is identified. The state dependent content is content that is renderable to have a several appearances. The electronic document is presented to a user, which includes disclosing the presence of any identified state dependent content in the electronic document.

Abstract: Methods and apparatus, including computer program products, implementing and using techniques for controlling capabilities of a user software application. A user software application is provided, the user software application including a set of disabled operations. Content capable of being operated on by one or more of the disabled operations in the set of disabled operations is received. Application rights information operable to enable an operation in the set of disabled operations to operate on content within a context specified in the application rights information are received and the operation in the set of disabled operations is enabled to operate on the received content. Methods and apparatus for providing content to be operated on by a user software application and methods and apparatus for providing a configurable, context-dependent user software application are also described.