changing cipher for imap clients

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The funny thing is AES128 may be harder to break than AES256. 

https://www.schneier.com/blog/archives/2009/07/another_new_aes.html

It had been a decade, so it would be interesting if Bruce Schneier has the same opinion. 

I just use the defaults. 





	  Original Message  



From: dovecot at dovecot.org
Sent: October 28, 2019 7:13 AM
To: dovecot at dovecot.org
Reply-to: 400thecat at gmx.ch
Subject: changing cipher for imap clients


When my client connects, I see this in my log:

  dovecot:  imap-login: TLSv1 with cipher ECDHE-RSA-AES128-SHA (128/128
bits)

Whereas, when client connects to my postfix server, I see:

  Anonymous TLS connection established from * TLSv1 with cipher
ECDHE-RSA-AES256-SHA (256/256 bits)

how can I tell dovecot to use AES256, instead of AES128 ?

is this set by ssl_cipher_list ? Here are my current values (defaults)

# doveconf ssl_cipher_list
ssl_cipher_list =
ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW at STRENGTH

# dovecot --version
2.3.4.1

thanks,