I want to use VoltDB's HTTP JSON interface
http://voltdb.com/docs/UsingVoltDB/ProgLangJson.php
section 15.2.1

I also want to use certificate based authentication of the client. I am thinking that I can use nginx as SSL frontend and have it rewrite the URL to include a randomly generated username and password as required by VoltDB. But, I can't figure out how to write the rewrite rule in nginx's conf file. I need to write multiple rules like this:
if client certificate common name is X, add to URL the arguments, user=PRF(x, u)&password=PRF(x, p) where PRF is a pseudo random function

Is this possible? How? I appreciate your help!