From 2bc8def078639dbaec99bc4ea5f58782f4d7decf Mon Sep 17 00:00:00 2001
From: Jamie Cameron <jcameron@webmin.com>
Date: Sat, 17 Sep 2022 16:40:12 -0700
Subject: [PATCH] Use ed25519 key if supported
 https://github.com/webmin/webmin/issues/1739

---
 sshd/sshd-lib.pl         | 11 +++++++++++
 sshd/useradmin_update.pl |  9 ++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/sshd/sshd-lib.pl b/sshd/sshd-lib.pl
index caa938c09..5989aed60 100755
--- a/sshd/sshd-lib.pl
+++ b/sshd/sshd-lib.pl
@@ -377,5 +377,16 @@ return &ui_radio($name, lc($value) eq 'yes' ? 1 :
 		   [ 2, $text{'default'} ] ]);
 }
 
+sub get_preferred_key_type
+{
+if ($version{'type'} eq 'openssh' && $version{'number'} >= 6.5) {
+	return "ed25519";
+	}
+if ($version{'type'} eq 'openssh' && $version{'number'} >= 3.2) {
+	return "rsa1";
+	}
+return undef;
+}
+
 1;
 
diff --git a/sshd/useradmin_update.pl b/sshd/useradmin_update.pl
index 7cd11f574..2852ade80 100755
--- a/sshd/useradmin_update.pl
+++ b/sshd/useradmin_update.pl
@@ -9,15 +9,14 @@ my ($uinfo) = @_;
 if ($config{'sync_create'} && &has_command($config{'keygen_path'}) &&
     -d $uinfo->{'home'} && !-d "$uinfo->{'home'}/.ssh") {
 	local $cmd;
-	local $type = $config{'sync_type'} ? "-t $config{'sync_type'}" :
-		      $version{'type'} eq 'openssh' &&
-		       $version{'number'} >= 3.2 ? "-t rsa1" : "";
+	local $type = $config{'sync_type'} || &get_preferred_key_type();
+	local $tflag = $type ? "-t $type" : "";
 	if ($config{'sync_pass'} && $uinfo->{'passmode'} == 3) {
-		$cmd = "$config{'keygen_path'} $type -P ".
+		$cmd = "$config{'keygen_path'} $tflag -P ".
 		       quotemeta($uinfo->{'plainpass'});
 		}
 	else {
-		$cmd = "$config{'keygen_path'} $type -P \"\"";
+		$cmd = "$config{'keygen_path'} $tflag -P \"\"";
 		}
 	&system_logged("echo '' | ".&command_as_user($uinfo->{'user'}, 0, $cmd).
 		       " >/dev/null 2>&1");