[HACKERS] SCRAM auth and Pgpool-II

Hi PostgreSQL hackers,

I would like to hear ideas how Pgpool-II can deal with SCRAM auth
which will be in PostgreSQL 10.

For those who are not familiar with Pgpool-II[1], it is an external
OSS project to provide some additional features to PostgreSQL,
including load balancing and automatic failover. Pgpool-II works as a
proxy between PostgreSQL client and PostgreSQL server(s).

When a client wants to connects to PostgreSQL and SCRAM auth is
enabled, it sends user name to server. Then the server sends
information including a salt to the client. The client computes a
"ClientProof" using the salt and other information, and sends it to
the server[2].

For Pgpool-II, things would go as follows:

1) clients sends user name to Pgpool-II.
2) Pgpool-II forwards it to PostgreSQL servers.
3) Each PostgreSQL server sends their own salt to Pgpool-II.
4) Pgpool-II is confused because there are multiple salts and each has  different values. The client only accepts
singlesalt obviously.
 

So my question is, is there any solution or workaround for the problem
#4. Someone at PGCon 2017 suggested that the problem could be avoided
if the auth method between the client and Pgpool-II is "trust" (which
means no auth). But this does not seem to be a best solution for me
because it would weaken the security.

I suspect this problem may not be specific to Pgpool-II. Any middle
ware which handles multiple PostgreSQL servers could have the similar
problem.

Any suggestion would be appreciated. Thanks in advance.

[1] https://pgpool.net
[2] https://tools.ietf.org/html/rfc5802#section-3
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp