12. A method for secure distribution of digital content from a content server over a network to a user running a browser program in a workstation connected to the network, the method comprising: (a) downloading a secure viewer program into the browser; (b) sending a request for a document containing content from the viewer program to the content server; (c) downloading an encrypted version of the requested document from the content server to the viewer; (d) computing a document identifier in the viewer as a result of a numerical calculation using as one input encrypted content in the encrypted version of the requested document and as another input information that is downloaded with the viewer program, which document identifier cannot be derived solely from the encrypted version of the requested document, and sending the document identifier to the content server; (e) downloading a decryption key to the viewer program from the content server in response to the document identifier; and (f) decrypting the encrypted version of the document in the viewer program and presenting the document content to the user.
12. A method for secure distribution of digital content from a content server over a network to a user running a browser program in a workstation connected to the network, the method comprising: (a) downloading a secure viewer program into the browser; (b) sending a request for a document containing content from the viewer program to the content server; (c) downloading an encrypted version of the requested document from the content server to the viewer; (d) computing a document identifier in the viewer as a result of a numerical calculation using as one input encrypted content in the encrypted version of the requested document and as another input information that is downloaded with the viewer program, which document identifier cannot be derived solely from the encrypted version of the requested document, and sending the document identifier to the content server; (e) downloading a decryption key to the viewer program from the content server in response to the document identifier; and (f) decrypting the encrypted version of the document in the viewer program and presenting the document content to the user. 15. The method of claim 12 wherein step (d) comprises computing the document identifier from the encrypted document content and a text string embedded in the viewer code.