Patent ID: 7496767

Claim:
A secure content object for distributing and controlling access to a document and annotations associated with the document, comprising: an electronic document, the electronic document having been encrypted with a document encryption key, wherein access to the electronic document is available to a first set of authorized users; an encrypted header comprising information pertaining to the electronic document; a first multi-key encryption table for use in a multi-key encryption method associated with the electronic document, the first table comprising at least one multi-key component associated with each authorized user in the first set and a plurality of dummy encryption components, wherein the multi-key encryption table includes no information that may identify a user or the electronic document; a plurality of annotations associated with the electronic document, generated by an annotation author and having been encrypted with an annotation encryption key, wherein access to the plurality of annotations is available to authorized annotation users comprising the annotation author and those users in the first set having been designated by the annotation author as having access to the plurality of annotations; a second multi-key encryption table for use in a multi-key encryption method associated with the plurality of annotations, the second table comprising at least one multi-key component associated with each authorized annotation user; and a user interface device comprising unencrypted information for identifying the electronic document and an interactive element for enabling a user to input a user authorization for access to at least a portion of the encrypted electronic document, for inputting the user authorization to a decryption engine using the multi-key encryption method for combining the user authorization with each of the multi-key components in the first multi-key encryption key table to decrypt the encrypted header, and for combining the user authorization with each of the stored multi-key components in the second multi-key encryption key table to decrypt an annotation, wherein upon a valid decryption of the annotation indicates the correct annotation encryption key has been found and the user is an authorized annotation user; and upon a valid decryption of the encrypted header, for enabling decryption of the portion of the encrypted electronic document.