acmetool: use ECDSA keys instead of RSA

Author: link2xt

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## untagged
 
+- acmetool: use ECDSA keys instead of RSA
+  ([#689](https://github.com/chatmail/relay/pull/689))
+
 - Require TLS 1.2 for outgoing SMTP connections
   ([#685](https://github.com/chatmail/relay/pull/685))
 

cmdeploy/src/cmdeploy/acmetool/target.yaml.j2

@@ -1,7 +1,8 @@
 request:
   provider: https://acme-v02.api.letsencrypt.org/directory
   key:
-    type: rsa
+    type: ecdsa
+    ecdsa-curve: nistp256
   challenge:
     webroot-paths:
     - /var/www/html/.well-known/acme-challenge