Method for digital signatures

摘要

Methods and systems for digital rights management are disclosed that allows the author of a design file to encrypt the files contents so that only authorized users can view the file, and that allows the author to identify specific users called recipients (104) for authorization. The author then designates (106) the rights granted to the recipients. Preferably the author identifies users and users are authenticated by means of the user's digital certificates. The author may also have the ability to specify what operations (110) a given user can perform, including view, print/plot, export, copy to clipboard, access history and edit. An author can also digitally sign a document or file using their digital certificate. A hash value is created for the item to be signed. The hash value is encrypted using a private key specified by the digital certificate and secured to the item. The hash value is verified by a recipient to determine if the item was modified.