From 61ffe1a147973947195bc1c8390b2fc8c50f2145 Mon Sep 17 00:00:00 2001
From: terrafrost <terrafrost@php.net>
Date: Tue, 7 Jan 2020 00:20:47 -0600
Subject: [PATCH] SSH2: fix rare key exchange issue

---
 phpseclib/Net/SSH2.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index 0e58b643..59fba230 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -1616,7 +1616,9 @@ class SSH2
         $temp = unpack('Nlength', substr($this->signature, 0, 4));
         $this->signature_format = substr($this->signature, 4, $temp['length']);
         $keyBytes = DH::computeSecret($ourPrivate, $theirPublicBytes);
-        if (($keyBytes[0] & "\x80") === "\x80") {
+        if (($keyBytes & "\xFF\x80") === "\x00\x00") {
+            $keyBytes = substr($keyBytes, 1);
+        } elseif (($keyBytes[0] & "\x80") === "\x80") {
             $keyBytes = "\0$keyBytes";
         }