How to encrypt proxy cache

[sachin.shetty@gmail.com]

Thanks Maxim for the reply. We have evaluated disk based encryption etc, but
that does not prevent sysadmins from viewing user data which is a problem
for us. 

Do you think we could build something using lua and intercept read and
wriite call from cache?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,273311,273354#msg-273354