From: Tom Lane <tgl@sss.pgh.pa.us>
To: Stephen Frost <sfrost@snowman.net>
cc: raf@raf.org, pgsql-bugs@lists.postgresql.org
Subject: Re: Possible to store invalid SCRAM-SHA-256 Passwords
In-reply-to: <20190423144159.GP6197@tamriel.snowman.net>
References: <016deb6b-1f0a-8e9f-1833-a8675b170aa9@postgresql.org>
 <4240a41f-a957-fd7d-7c24-31683f259b9d@postgresql.org>
 <20190422015051.GA3433@paquier.xyz> <3033.1555940554@sss.pgh.pa.us>
 <20190422135215.GG6197@tamriel.snowman.net>
 <20190422214924.pytigrzlq7mkdyzq@raf.org>
 <20190423144159.GP6197@tamriel.snowman.net>
Comments: In-reply-to Stephen Frost <sfrost@snowman.net>
	message dated "Tue, 23 Apr 2019 10:42:00 -0400"
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Date: Tue, 23 Apr 2019 10:55:28 -0400
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Stephen Frost <sfrost@snowman.net> writes:
> * raf@raf.org (raf@raf.org) wrote:
>> I don't think there's anything wrong with prefixing a
>> password hash with an identifier for the password
>> hashing scheme (and any parameters for that scheme).
>> This is done all the time in many systems. It just has
>> to be unambiguoous.

> There isn't a way to make it unambiguous given that we accept
> more-or-less anything as a plaintext password though, that would be the
> issue here..

In practice, particularly with the extra validation we just added,
it seems vanishingly unlikely that anyone would choose a password
that just happened to look like one of the hashed formats.

If somebody intentionally chooses such a password, well, it's on
their heads whether the outcome is what they want.

			regards, tom lane