diff --git a/build-windows.ps1 b/build-windows.ps1
index 38d2525..6a28833 100644
--- a/build-windows.ps1
+++ b/build-windows.ps1
@@ -86,12 +86,35 @@ Copy-Item $uptermExe.FullName "C:\Windows\System32\upterm.exe" -Force
 Remove-Item $tarGz, $extractDir -Recurse -Force -ErrorAction SilentlyContinue
 Write-Host "      OK - upterm $version installiert"
 
+# 3. SSH-Key erzeugen (upterm benoetigt publickey-Auth)
+Write-Host "[3/3] Pruefe SSH-Key..."
+$sshDir    = "$env:USERPROFILE\.ssh"
+$keyFile   = "$sshDir\id_ed25519"
+New-Item -ItemType Directory -Force -Path $sshDir | Out-Null
+
+if (Test-Path $keyFile) {
+    Write-Host "      OK (Key vorhanden: $keyFile)"
+} else {
+    $sshKeygen = "$env:SystemRoot\System32\OpenSSH\ssh-keygen.exe"
+    if (-not (Test-Path $sshKeygen)) { $sshKeygen = "ssh-keygen" }
+    Write-Host "      Generiere neuen ed25519-Key..."
+    & $sshKeygen -t ed25519 -N '""' -f $keyFile 2>&1 | Out-Null
+    if (Test-Path $keyFile) {
+        Write-Host "      OK (Key erstellt: $keyFile)"
+    } else {
+        Write-Host "      WARNUNG: ssh-keygen nicht verfuegbar."
+        Write-Host "      Bitte OpenSSH-Client installieren:"
+        Write-Host "      Einstellungen > Apps > Optionale Features > OpenSSH-Client"
+        Write-Host "      Danach: ssh-keygen -t ed25519 -N """" -f $keyFile"
+    }
+}
+
 Write-Host ""
 Write-Host "============================================================"
 Write-Host " Installation abgeschlossen!"
 Write-Host "============================================================"
 Write-Host ""
-Write-Host " PowerShell NEU STARTEN, dann Session teilen mit:"
+Write-Host " Session teilen mit:"
 Write-Host ""
 Write-Host "   upterm host --server ssh://upterm.ebesch.de:2222 --accept"
 Write-Host ""