Date: Tue, 22 Dec 2020 16:13:06 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Alastair Turner <minion@decodable.me>
Cc: Stephen Frost <sfrost@snowman.net>,
	Michael Paquier <michael@paquier.xyz>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Masahiko Sawada <masahiko.sawada@2ndquadrant.com>
Subject: Re: Proposed patch for key managment
Message-ID: <20201222211306.GA9170@momjian.us>
References: <20201218213624.GG16415@tamriel.snowman.net>
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 <20201220225909.GJ16415@tamriel.snowman.net>
 <20201221213514.GK28841@momjian.us>
 <20201222030748.GN28841@momjian.us>
 <20201222154017.GO28841@momjian.us>
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On Tue, Dec 22, 2020 at 08:15:27PM +0000, Alastair Turner wrote:
> Hi Bruce
> 
> In ckey_passphrase.sh.sample
> 
> +
> +echo "$PASS" | sha256sum | cut -d' ' -f1
> +
> 
> Under the threat model discussed, a copy of the keyfile could be
> attacked offline. So getting from passphrase to DEKs should be as
> resource intensive as possible to slow down brute-force attempts.
> Instead of just a SHA hash, this should be at least a PBKDF2 (PKCS#5)

I am satisfied with the security of SHA256.

> On Tue, 22 Dec 2020 at 15:40, Bruce Momjian <bruce@momjian.us> wrote:
> >
> > Here is an updated patch.  Are people happy with the Makefile, its
> > location in the source tree, and the install directory name?  I used the
> > directory name 'auth_commands' because I thought 'auth' was too easily
> > misinterpreted. I put the scripts in /src/backend/utils/auth_commands.
> >
> 
> What's implemented in these patches is an internal keystore, wrapped
> with a key derived from a passphrase. I'd think that the scripts
> directory should reflect what they interact with, so
> 'keystore_commands' or 'local_keystore_command' sounds more specific
> and therefore better than 'auth_commands'.

The point is that some commands are used for keystore and some for SSL
certificate passphrase entry, hence "auth".

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee