Feature request SCRAM-SHA-256

[Tributh]

Am 16.12.18 um 09:42 schrieb Aki Tuomi:
> 
>> On 16 December 2018 at 10:27 Tributh via dovecot <dovecot at dovecot.org> wrote:
>>
>>
>> Hi,
>> is that here the right place to make feature requests?
>>
>> dovecot supports as authentication mechanism
>> SCRAM-SHA-1 from RFC 5802
>> which was updated to
>> SCRAM-SHA-256 in RFC 7677
>>
>> Can SCRAM-SHA-256 be added to the authentication mechanisms?
>>
>> I would not like to request, that SCRAM-SHA-1 will be exchanged by
>> SCRAM-SHA-256, since several applications only support SCRAM-SHA-1
>>
>> Regards
>>
>> Torsten
> 
> Hi!
> 
> Adding this is possible, it can even be done as a separate plugin. But I have to ask, why? Do you actually have clients that support this?
> 
> Aki
> 
Hi Aki,
let me first answer the second question.
Sadly I have no client which supports it, yet.
Here we have a chicken or the egg causality dilemma.
There was some communication with mail-client developers which stated
that they would start developing it, when they have a publicly usable
server to test against.
Now I hope that the most common IMAP server could be the one, which
gives this possibility.
Sadly, most communication is not publicly available.

In the past CRAM-MD5 was very popular. When the insecurity came out,
everything just shifted to TLS, but that prevented not from sending a
plain password now. If a malicious actor is able to change DNS/TLS
endpoints, he will receive the plain passwords immediately.
I am not the expert in explaining how such an actor could do this. I
just wanted to have possibilities for everybody to prevent this possible
exposure of a plain password, which could than easily used abusively.

I just hope for better security in the future.

Regards Torsten