From 14156235863358631c3ff0d2917513b9c9280eba Mon Sep 17 00:00:00 2001
From: Martin Weinelt <hexa@darmstadt.ccc.de>
Date: Fri, 19 Dec 2025 03:13:27 +0100
Subject: [PATCH 1/2] dovecot: support X25519MLKEM768 hybrid kex

---
 mail-server/dovecot.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mail-server/dovecot.nix b/mail-server/dovecot.nix
index 6248351..9d401cc 100644
--- a/mail-server/dovecot.nix
+++ b/mail-server/dovecot.nix
@@ -368,7 +368,7 @@ in
         ssl = required
         ssl_min_protocol = TLSv1.2
         ssl_prefer_server_ciphers = no
-        ssl_curve_list = X25519:prime256v1:secp384r1
+        ssl_curve_list = X25519MLKEM768:X25519:prime256v1:secp384r1
 
         service lmtp {
           unix_listener dovecot-lmtp {

From 3579eb0001300243b505cafee426eb8e6fca1315 Mon Sep 17 00:00:00 2001
From: Martin Weinelt <hexa@darmstadt.ccc.de>
Date: Fri, 19 Dec 2025 03:33:34 +0100
Subject: [PATCH 2/2] dovecot: restrict TLS cipher suites

---
 mail-server/dovecot.nix | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/mail-server/dovecot.nix b/mail-server/dovecot.nix
index 9d401cc..13f68bb 100644
--- a/mail-server/dovecot.nix
+++ b/mail-server/dovecot.nix
@@ -368,6 +368,18 @@ in
         ssl = required
         ssl_min_protocol = TLSv1.2
         ssl_prefer_server_ciphers = no
+        ssl_cipher_list = ${
+          lib.concatStringsSep ":" [
+            # TLS1.3
+            "TLS_AES_128_GCM_SHA256"
+            "TLS_CHACHA20_POLY1305_SHA256"
+            "TLS_AES_256_GCM_SHA384"
+            # TLS1.2
+            "ECDHE-ECDSA-AES128-GCM-SHA256"
+            "ECDHE-ECDSA-CHACHA20-POLY1305"
+            "ECDHE-ECDSA-AES256-GCM-SHA384"
+          ]
+        }
         ssl_curve_list = X25519MLKEM768:X25519:prime256v1:secp384r1
 
         service lmtp {