Re: MD5 authentication needs help

On Wed, Mar  4, 2015 at 01:27:32PM -0500, Stephen Frost wrote:
> This further makes what is sent over the network not directly
> susceptible to a replay attack because the server has multiple values
> available to pick for the salt to use and sends one at random to the
> client, exactly how our current challenge/response replay-prevention
> system works.  The downside is that the number of possible values for
> the server to send to prevent replay attacke is reduced from 2^32 to N.

OK, I understand now --- by not using a random session salt, you can
store a post-hash of what you receive from the client, preventing the
pg_authid from being resent by a client.  Nice trick, though going from
2^32 to N randomness doesn't seem like a win.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + Everyone has their own god. +