Le 13 févr. 2019 à 14:54, Robert Moskowitz via dovecot <dovecot@dovecot.org> a écrit :

On 2/13/19 8:30 AM, Aki Tuomi wrote:

On 13.2.2019 15.18, Robert Moskowitz via dovecot wrote:

On 2/13/19 1:23 AM, Matthias Fechner via dovecot wrote:

Am 13. Februar 2019 00:34:15 schrieb Robert Moskowitz
<rgm@htt-consult.com>:

On 2/12/19 6:03 PM, Matthias Fechner via dovecot wrote:

Am 12.02.2019 um 17:05 schrieb Robert Moskowitz via dovecot:

I have trying to find how to set the dovecot-sql.conf for using
SHA256/512. I am going to start clean with the stronger format, not
migrate from the old MD5. It seems all I need is:

you maybe would like to have a look to the hashing algo ARGON2I
which is
currently recommended for new developments and deployments.

Recommended by whom?

Can you provide a link?

Sure, please see here:
https://www.owasp.org/index.php/Password_Storage_Cheat_Sheet

And if I was adventurous about hashes, I would be looking more at
Keccak.

Check out my Internet Draft:

draft-moskowitz-small-crypto-00.txt

Thanks for the tip, will have a look for into it.

Keccak is a general hashing function. It was the first? of the
hashing 'sponge' functions, that many have followed. It is the basis
of SHA3 (at Keccak's greatest strength).

Argon2 seems to be special-built for password hashing. Thing is it is
not supported on my CentOS7 system:

# doveadm pw -l
MD5 MD5-CRYPT SHA SHA1 SHA256 SHA512 SMD5 SSHA SSHA256 SSHA512 PLAIN
CLEAR CLEARTEXT PLAIN-TRUNC CRAM-MD5 SCRAM-SHA-1 HMAC-MD5 DIGEST-MD5
PLAIN-MD4 PLAIN-MD5 LDAP-MD5 LANMAN NTLM OTP SKEY RPA PBKDF2 CRYPT
SHA256-CRYPT SHA512-CRYPT

Of course SHA3 is not listed either...

ARGON2 support is added in dovecot v2.3. It also needs to be enabled
when compiling dovecot, so varying from packagers it might or not be
available. The CRYPT ones are available if crypt(3) supports them. In
dovecot v2.3 we have added bcrypt support regardless of crypt(3) support.

CentOS7 is on dovecot 2.2.36:

# doveadm pw -s ARGON2-CRYPT -p secret
Fatal: Unknown scheme: ARGON2-CRYPT
# doveadm pw -s ARGON2 -p secret
Fatal: Unknown scheme: ARGON2

I tend to stay with the distro's rpms and not take on building and maintaining myself.