From 826d8d6670855e885d34595843e9fe0fb875b02b Mon Sep 17 00:00:00 2001
From: terrafrost <terrafrost@gmail.com>
Date: Sun, 31 Jul 2022 17:14:20 -0500
Subject: [PATCH] make it so OpenSSH encrypted keys can be created

---
 .../Crypt/Common/Formats/Keys/OpenSSH.php     | 26 ++++++++++++++-----
 tests/Unit/Crypt/EC/KeyTest.php               |  9 +++++++
 2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php b/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php
index ff66e256..3807e2a2 100644
--- a/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php
+++ b/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php
@@ -88,6 +88,9 @@ abstract class OpenSSH
                 case 'none':
                     break;
                 case 'aes256-ctr':
+                    if ($kdfname != 'bcrypt') {
+                        throw new \RuntimeException('Only the bcrypt kdf is supported (' . $kdfname . ' encountered)');
+                    }
                     list($salt, $rounds) = Strings::unpackSSH2('sN', $kdfoptions);
                     $crypto = new AES('ctr');
                     //$crypto->setKeyLength(256);
@@ -95,7 +98,7 @@ abstract class OpenSSH
                     $crypto->setPassword($password, 'bcrypt', $salt, $rounds, 32);
                     break;
                 default:
-                    throw new \RuntimeException('The only supported cipherse are: none, aes256-ctr (' . $ciphername . ' is being used');
+                    throw new \RuntimeException('The only supported cipherse are: none, aes256-ctr (' . $ciphername . ' is being used)');
             }
 
             list($publicKey, $paddedKey) = Strings::unpackSSH2('ss', $key);
@@ -178,10 +181,6 @@ abstract class OpenSSH
      */
     protected static function wrapPrivateKey($publicKey, $privateKey, $password, $options)
     {
-        if (!empty($password) && is_string($password)) {
-            throw new UnsupportedFormatException('Encrypted OpenSSH private keys are not supported');
-        }
-
         list(, $checkint) = unpack('N', Random::string(4));
 
         $comment = isset($options['comment']) ? $options['comment'] : self::$comment;
@@ -189,6 +188,8 @@ abstract class OpenSSH
                      $privateKey .
                      Strings::packSSH2('s', $comment);
 
+        $usesEncryption = !empty($password) && is_string($password);
+
         /*
            from http://tools.ietf.org/html/rfc4253#section-6 :
 
@@ -196,11 +197,22 @@ abstract class OpenSSH
            'padding_length', 'payload', and 'random padding' MUST be a multiple
            of the cipher block size or 8, whichever is larger.
          */
-        $paddingLength = (7 * strlen($paddedKey)) % 8;
+        $blockSize = $usesEncryption ? 16 : 8;
+        $paddingLength = (($blockSize - 1) * strlen($paddedKey)) % $blockSize;
         for ($i = 1; $i <= $paddingLength; $i++) {
             $paddedKey .= chr($i);
         }
-        $key = Strings::packSSH2('sssNss', 'none', 'none', '', 1, $publicKey, $paddedKey);
+        if (!$usesEncryption) {
+            $key = Strings::packSSH2('sssNss', 'none', 'none', '', 1, $publicKey, $paddedKey);
+        } else {
+            $rounds = isset($options['rounds']) ? $options['rounds'] : 16;
+            $salt = Random::string(16);
+            $kdfoptions = Strings::packSSH2('sN', $salt, $rounds);
+            $crypto = new AES('ctr');
+            $crypto->setPassword($password, 'bcrypt', $salt, $rounds, 32);
+            $paddedKey = $crypto->encrypt($paddedKey);
+            $key = Strings::packSSH2('sssNss', 'aes256-ctr', 'bcrypt', $kdfoptions, 1, $publicKey, $paddedKey);
+        }
         $key = "openssh-key-v1\0$key";
 
         return "-----BEGIN OPENSSH PRIVATE KEY-----\n" .
diff --git a/tests/Unit/Crypt/EC/KeyTest.php b/tests/Unit/Crypt/EC/KeyTest.php
index 979d3c59..8b15b5af 100644
--- a/tests/Unit/Crypt/EC/KeyTest.php
+++ b/tests/Unit/Crypt/EC/KeyTest.php
@@ -565,4 +565,13 @@ MIIEDwIBADATBgcqhkjOPQIBBggqhkjOPQMBBwSCA/MwggPvAgEBBIID6P//////
 
         $this->assertSameNL($raw, $key->toString('MontgomeryPrivate'));
     }
+
+    public function testOpenSSHEncryptedCreation()
+    {
+        $key = EC::createKey('Ed25519');
+        $key = $key->withPassword('test')->toString('OpenSSH');
+
+        $key = PublicKeyLoader::load($key, 'test');
+        $this->assertInstanceOf(PrivateKey::class, $key);
+    }
 }