note sundialsvc4 <p> The approach that I would take here is ... secure the <em>channel.</em> &nbsp; Use certificates to authenticate the users (and to secure the communications with each). &nbsp; Use existing standard protocols to do this, not one that you have rolled. &nbsp; Put the information on a highly-secured server which will only communicate with bearers of currently-valid credentials. &nbsp; The information that passes through the secured channel can be plaintext, since it passes between parties with mutually-assured identities. &nbsp; The database files are encrypted using a key known only to the server: &nbsp; these services are already readily-available in any major server. &nbsp; I would advocate avoiding use of deterministic encryption altogether, because I do not think it will ever provide the data-security and data-integrity that you need. </p><p> I fail to see why you should be having to &ldquo;roll your own <em>anything&rdquo;</em> to accomplish this... &nbsp; This is hardly an atypical or novel requirement. </p> 877274 877274