From 055d6097af6fb3359e2f7ef8a804d02b785eca33 Mon Sep 17 00:00:00 2001
From: terrafrost <terrafrost@php.net>
Date: Tue, 15 Jan 2019 23:41:49 -0600
Subject: [PATCH] SSH2: more strictly adhere to RFC8332 for rsa-sha2-256/512

---
 phpseclib/Net/SSH2.php | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index 6c08156f..026f5e26 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -2687,6 +2687,21 @@ class Net_SSH2
             $publickey['n']
         );
 
+        switch ($this->signature_format) {
+            case 'rsa-sha2-512':
+                $hash = 'sha512';
+                $signatureType = 'rsa-sha2-512';
+                break;
+            case 'rsa-sha2-256':
+                $hash = 'sha256';
+                $signatureType = 'rsa-sha2-256';
+                break;
+            //case 'ssh-rsa':
+            default:
+                $hash = 'sha1';
+                $signatureType = 'ssh-rsa';
+        }
+
         $part1 = pack(
             'CNa*Na*Na*',
             NET_SSH2_MSG_USERAUTH_REQUEST,
@@ -2697,7 +2712,7 @@ class Net_SSH2
             strlen('publickey'),
             'publickey'
         );
-        $part2 = pack('Na*Na*', strlen('ssh-rsa'), 'ssh-rsa', strlen($publickey), $publickey);
+        $part2 = pack('Na*Na*', strlen($signatureType), $signatureType, strlen($publickey), $publickey);
 
         $packet = $part1 . chr(0) . $part2;
         if (!$this->_send_binary_packet($packet)) {
@@ -2738,23 +2753,9 @@ class Net_SSH2
 
         $packet = $part1 . chr(1) . $part2;
         $privatekey->setSignatureMode(CRYPT_RSA_SIGNATURE_PKCS1);
-        switch ($this->signature_format) {
-            case 'rsa-sha2-512':
-                $hash = 'sha512';
-                $type = 'rsa-sha2-512';
-                break;
-            case 'rsa-sha2-256':
-                $hash = 'sha256';
-                $type = 'rsa-sha2-256';
-                break;
-            //case 'ssh-rsa':
-            default:
-                $hash = 'sha1';
-                $type = 'ssh-rsa';
-        }
         $privatekey->setHash($hash);
         $signature = $privatekey->sign(pack('Na*a*', strlen($this->session_id), $this->session_id, $packet));
-        $signature = pack('Na*Na*', strlen($type), $type, strlen($signature), $signature);
+        $signature = pack('Na*Na*', strlen($signatureType), $signatureType, strlen($signature), $signature);
         $packet.= pack('Na*', strlen($signature), $signature);
 
         if (!$this->_send_binary_packet($packet)) {