Re: password_encryption, default and 'plain' support

Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
> On 05/03/2017 07:14 PM, Tom Lane wrote:
>> Is it possible that there are still client libraries that don't support
>> password encryption at all? If so, are we willing to break them?
>> I'd say "yes" but it's worth thinking about.

> That doesn't make sense. The client doesn't even know what
> password_encryption is set to. I think you're confusing
> password_encryption='plain' with the plaintext "password" authentication
> method.

Ah, you're right.

> If the server has an MD5 hash stored in pg_authid, the server will ask
> the client to do MD5 authentication. If the server has a SCRAM verifier
> in pg_authid, it will ask the client to do SCRAM authentication. If the
> server has a plaintext password in pg_authid, it will also ask the
> client to do SCRAM authentication (it could ask for MD5 authentication,
> but as the code stands, it will ask for SCRAM).

Um. That would be a backwards compatibility break ... but it doesn't
matter if we get rid of the option to store in plaintext.

The other question I can think to ask is what will happen during
pg_upgrade, given an existing installation with one or more passwords
stored plain. If the answer is "silently convert to MD5", I'd be
good with that.

regards, tom lane