Abstract: An apparatus includes a computer executable for processing a file of a first file type, and a Hypertext Transfer Protocol (“HTTP”) client that receives files of the first type and a second type from a network. The HTTP client causes the computer executable to process files of the first type. The computer executable includes a first module that determines whether the file includes a first content type and performs a first function if the file includes the first content type. The computer executable also includes a second module that determines whether the file includes a second content type and performs a second function different from the first function if the file includes the second content type.

Abstract: Methods and apparatus, including computer program products, for presenting status of digital signatures. A digital document is received that defines a presentation structure and includes a digital signature. The digital document specifies a representation of the digital signature and a location in the presentation structure for the representation of the digital signature. A status is determined for the digital signature. A status representation is associated with the digital signature, where the status representation identifies the status determined for the digital signature. Without altering the representation of the digital signature, at least a portion of the digital document and the status representation of the digital signature are presented in a user interface, where the status representation is presented in the presentation structure at a location that depends upon the location of the digital signature.

Abstract: Methods and apparatus, including computer program products, implementing and using techniques for signing an electronic document, including establishing an electronic signature appearance for an electronic signature, determining a bounding region on the electronic document for the display of the electronic signature appearance, at the time of signing an electronic document, previewing the electronic signature appearance in the bounding region and signing the electronic document with an electronic signature, the electronic signature associated with the electronic signature appearance. The electronic signature appearance can be configured at the time of signing the electronic document.

Abstract: A method includes receiving a request to access a digital content item, the digital content item including multiple portions. Responsive to the request, multiple policies relating respectively to the multiple portions of the digital content item are identified. Access to the multiple portions of the digital content item is selectively enabled, based on the multiple policies.

Abstract: Active content is deterministically rendered in a stable format that is independent of any particular targeted environment, which the active content may subsequently be rendered to. Environmental and dynamic dependencies are removed from a specification associated with the active content for purposes of producing a stable and consistent specification for the active content. The stable and static specification is used to subsequently render the active content into the stable format for any targeted or desired environment.

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 digital rights management. An electronic document containing one or more content items is provided along with a set of usage rights. The set of usage rights defines one or more features to be enabled when the electronic document is processed in an electronic document reader. A representation of a set of content items of the electronic document that are invariant to operations of the features in the set of usage rights is generated, and a digital signature authorizing the set of usage rights is provided. An electronic document and an electronic document reader are also described.

Abstract: An apparatus includes a computer executable for processing a file of a first file type, and a Hypertext Transfer Protocol (“HTTP”) client that receives files of the first type and a second type from a network. The HTTP client causes the computer executable to process files of the first type. The computer executable includes a first module that determines whether the file includes a first content type and performs a first function if the file includes the first content type. The computer executable also includes a second module that determines whether the file includes a second content type and performs a second function different from the first function if the file includes the second content type.

Abstract: Methods and apparatus for creating a license defining permissions to use electronic content. The methods include selecting a plurality of habitat types, each an aspect of a user environment to which a license can be bound, the selection based on input from a retail customer; determining one or more habitat values and relations for each selected type; and creating a license to use the electronic content, the license including an and-or logic expression of habitat terms, each term containing one of the selected types and its set of corresponding values and relations. Each habitat term may include a key for decrypting or unlocking the electronic content.

Abstract: Methods and apparatus implementing a technique for retrieving requested data. In general, in one aspect, the technique includes receiving a request from an application to read a portion of an application file and consulting a filter-system file. The filter-system file contains processed data that corresponds to data in the application file and correspondence information indicating how the set of processed data corresponds to the data in the application file. The technique also includes deriving the requested portion of the application file from the processed data using the correspondence information, and delivering the requested portion of the application file to the application.

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 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: A secured access to data in a portable document format (PDF) file is provided by encapsulating a Public Key Cryptography Standard number 7 (PKCS#7) object having a recipient list into data. ‘Enveloped data’ encapsulated in the PKCS#7 object contains access information that is used to access the remainder of the document into which the PKCS#7 object is encapsulated. The access information can be decrypted by all recipients in the PKCS#7 recipient list. If a recipient listed in the recipient list attempts to access data in the document, the access information is decrypted using the recipient's private key. The access information is used to obtain an access key that is used to decrypt data in the document.

Abstract: A method for providing secured access to a document includes the steps of embedding a permissions attribute into a recipient list. The permissions attribute identifies permissions allowing various levels of access to a predetermined document. Each recipient listed in the recipient list has a corresponding permission associated therewith. Further, the method renders the recipient list and its contents tamper-proof.