1. Apparatus 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 apparatus comprising: means for downloading a secure viewer program into the browser; means in the viewer program for requesting a document containing content from the content server; means in the content server for downloading an encrypted version of the requested document; means in the viewer for performing a numerical calculation, using as one input encrypted document content in the encrypted version of the requested document and as another input information that is downloaded with the viewer program, to compute as a result a document identifier that cannot be derived solely from the encrypted version of the requested document and sending the document identifier to the content server; means in the content server and responsive to the document identifier for downloading a decryption key to the viewer program; and means in the viewer program for decrypting the encrypted version of the document and presenting the document content to the user.
6. The apparatus of claim 1 further comprising a publishing tool that accepts plaintext documents, encrypts the plaintext documents and generates document identifiers for each encrypted document.