Allow pg_shadow to be MD5 encrypted.
Add ENCRYPTED/UNENCRYPTED option to CREATE/ALTER user.
Add password_encryption postgresql.conf option.
Update wire protocol version to 2.1.

files to restrict the set of users that can connect to a database
but can still use the pg_shadow password. (You just leave off the
password field in the secondary file.)

From: Tatsuo Ishii <t-ishii@sra.co.jp>

Ok. I made patches replacing all of "#if FALSE" or "#if 0" to "#ifdef
NOT_USED" for current. I have tested these patches in that the
postgres binaries are identical.

an illegal macro name.  Correct syntax is "#if 0".  This is in...

From: Darren King <darrenk@insightdist.com>

I've completed the patch to fix the protocol and authentication issues I
was discussing a couple of weeks ago.  The particular changes are:

- the protocol has a version number
- network byte order is used throughout
- the pg_hba.conf file is used to specify what method is used to
  authenticate a frontend (either password, ident, trust, reject, krb4
  or krb5)
- support for multiplexed backends is removed
- appropriate changes to man pages
- the -a switch to many programs to specify an authentication service
  no longer has any effect
- the libpq.so version number has changed to 1.1

The new backend still supports the old protocol so old interfaces won't
break.

                                        ^^^^

  o  A new patch that contains the following changes:
        -- The pg_pwd file is now cached in the postmaster's memory.
        -- pg_pwd is reloaded when the postmaster detects a flag file creat()'ed
           by a backend.
        -- qsort() is used to sort loaded password entries, and bsearch() is
           is used to find entries in the pg_pwd cache.
        -- backends now copy the pg_user relation to pg_pwd.pid, and then
           rename the temp file to be pg_pwd.
        -- The delimiter for pg_pwd has been changed to a tab character.

                                  ^^^^ gcc likes this