Horton

Re: Password identifiers, protocol aging and SCRAM protocol

Michael Paquier <michael.paquier@gmail.com>

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From: Michael Paquier <michael.paquier@gmail.com>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Robert Haas <robertmhaas@gmail.com>, Julian Markwort <julian.markwort@uni-muenster.de>, Magnus Hagander <magnus@hagander.net>, Stephen Frost <sfrost@snowman.net>, David Steele <david@pgmasters.net>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, Valery Popov <v.popov@postgrespro.ru>
Date: 2016-07-04T03:54:37Z
Lists: pgsql-hackers 
On Mon, Jul 4, 2016 at 6:34 AM, Peter Eisentraut
<peter.eisentraut@2ndquadrant.com> wrote:
> On 7/2/16 3:54 PM, Heikki Linnakangas wrote:
>>
>> In related news, RFC 7677 that describes a new SCRAM-SHA-256
>> authentication mechanism, was published in November 2015. It's identical
>> to SCRAM-SHA-1, which is what this patch set implements, except that
>> SHA-1 has been replaced with SHA-256. Perhaps we should forget about
>> SCRAM-SHA-1 and jump straight to SCRAM-SHA-256.
>
> I think a global change from SHA-1 to SHA-256 is in the air already, so if
> we're going to release something brand new in 2017 or so, it should be
> SHA-256.
>
> I suspect this would be a relatively simple change, so I wouldn't mind
> seeing a SHA-1-based variant in CF1 to get things rolling.

I'd just move this thing to SHA256, we are likely going to use that at the end.

As I am coming back into that, I would as well suggest do the
following, that the current set of patches is clearly missing:
- Put the HMAC infrastructure stuff of pgcrypto into src/common/. It
is a bit a shame to not reuse what is currently available, then I
would suggest to reuse that with HMAC_SCRAM_SHAXXX as label.
- Move *all* the SHA-related things of pgcrypto to src/common,
including SHA1, SHA224 and SHA256. px_memset is a simple wrapper on
top of memset, we should clean up that first.
Any other things to consider that I am forgetting?
-- 
Michael

Commits

  1. Support SCRAM-SHA-256 authentication (RFC 5802 and 7677).

  2. Refactor SHA2 functions and move them to src/common/.

  3. Replace isMD5() with a more future-proof way to check if pw is encrypted.

  4. Remove bogus notice that older clients might not work with MD5 passwords.

  5. Refactor the code for verifying user's password.

  6. Replace PostmasterRandom() with a stronger source, second attempt.

  7. Remove support for (insecure) crypt authentication.