release.ps1: signing key backup creates the folder, asks the password twice, verifies; -ImportSigningKey to restore

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

release.ps1

@@ -10,7 +10,8 @@
 # Signatur: jede Datei wird mit dem privaten Release-Schlüssel signiert (RSA-3072, SHA-256) - der Launcher und das Setup
 # installieren nur, was zu ihrem eingebauten öffentlichen Schlüssel passt. Selbst wer den Keymaster oder den Token
 # übernimmt, kann so keine fremde Datei als MSCO-Update verteilen. Der Schlüssel liegt DPAPI-verschlüsselt in
-# %USERPROFILE%\.msco\release-signing-key.dpapi (einmal anlegen: "release.ps1 -NewSigningKey"; SICHERN: "-ExportSigningKey").
+# %USERPROFILE%\.msco\release-signing-key.dpapi (einmal anlegen: "release.ps1 -NewSigningKey"; SICHERN: "-ExportSigningKey <datei>",
+# zurückspielen auf einem neuen PC: "-ImportSigningKey <datei>").
 # Gibt es die Version auf dem Keymaster schon, passiert nichts - also einfach die Version erhöhen und bauen.
 param(
     [ValidateSet("mod", "launcher", "installer")][string]$Product,
@@ -18,6 +19,7 @@ param(
     [switch]$SaveToken,
     [switch]$NewSigningKey,
     [string]$ExportSigningKey = "",
+    [string]$ImportSigningKey = "",
     [string]$Version = "",
     [string]$Changelog = ""
 )
@@ -54,6 +56,12 @@ if ($SaveToken) {
     exit 0
 }
 $keyEntropy = [Text.Encoding]::UTF8.GetBytes("MSCO release signing key v1")
+# Passwort für Backups: verdeckt fragen - oder aus MSCO_BACKUP_PASSWORD (für automatische Backups)
+function Get-BackupPassword([string]$prompt) {
+    if ($env:MSCO_BACKUP_PASSWORD) { return $env:MSCO_BACKUP_PASSWORD }
+    $secure = Read-Host $prompt -AsSecureString
+    return [Runtime.InteropServices.Marshal]::PtrToStringAuto([Runtime.InteropServices.Marshal]::SecureStringToBSTR($secure))
+}
 $keyFile = Find-Secret "release-signing-key.dpapi"
 
 # Neues Schlüsselpaar (nur einmal - der öffentliche Schlüssel ist in Launcher und Setup eingebaut)
@@ -72,20 +80,62 @@ if ($NewSigningKey) {
 if ($ExportSigningKey) {
     if (-not (Test-Path $keyFile)) { Write-Host "No signing key"; exit 1 }
     $private = [Security.Cryptography.ProtectedData]::Unprotect([IO.File]::ReadAllBytes($keyFile), $keyEntropy, $scope)
-    $pw = Read-Host "Password for the backup" -AsSecureString
+    $plainPw = Get-BackupPassword "Password for the backup"
-    $plainPw = [Runtime.InteropServices.Marshal]::PtrToStringAuto([Runtime.InteropServices.Marshal]::SecureStringToBSTR($pw))
     if ($plainPw.Length -lt 12) { Write-Host "Use at least 12 characters"; exit 1 }
+    # Zweimal fragen: ein Tippfehler machte das Backup sonst unbrauchbar
+    $plainPw2 = Get-BackupPassword "Repeat the password"
+    if ($plainPw2 -ne $plainPw) { Write-Host "The passwords do not match - nothing written"; exit 1 }
     $salt = New-Object byte[] 16; (New-Object Security.Cryptography.RNGCryptoServiceProvider).GetBytes($salt)
     $kdf = New-Object Security.Cryptography.Rfc2898DeriveBytes($plainPw, $salt, 300000, [Security.Cryptography.HashAlgorithmName]::SHA256)
     $aes = [Security.Cryptography.Aes]::Create(); $aes.Key = $kdf.GetBytes(32); $aes.GenerateIV()
     $enc = $aes.CreateEncryptor().TransformFinalBlock($private, 0, $private.Length)
     $out = "MSCO-SIGNING-KEY-BACKUP v1`n" + [Convert]::ToBase64String($salt) + "`n" + [Convert]::ToBase64String($aes.IV) + "`n" + [Convert]::ToBase64String($enc)
+    try {
+        $dir = Split-Path -Parent $ExportSigningKey
+        if ($dir -and -not (Test-Path -LiteralPath $dir)) { New-Item -ItemType Directory -Force -Path $dir | Out-Null }
         [IO.File]::WriteAllText($ExportSigningKey, $out)
-    Write-Host "Backup written to $ExportSigningKey (AES-256, PBKDF2-SHA256 300000) - keep it and the password safe"
+    } catch {
+        Write-Host "Could not write $ExportSigningKey : $($_.Exception.Message)"
+        Write-Host "Network drive? Drive letters like Z: are not visible in a PowerShell window that runs as administrator."
+        Write-Host "Use a normal (not elevated) PowerShell window, or the network path, e.g. \\server\share\folder\msco-signing-key-backup.txt"
+        exit 1
+    }
+    # Gegenprobe: Datei lesen und mit dem Passwort wieder entschlüsseln
+    $lines = [IO.File]::ReadAllText($ExportSigningKey).Split("`n")
+    $kdf2 = New-Object Security.Cryptography.Rfc2898DeriveBytes($plainPw, [Convert]::FromBase64String($lines[1]), 300000, [Security.Cryptography.HashAlgorithmName]::SHA256)
+    $aes2 = [Security.Cryptography.Aes]::Create(); $aes2.Key = $kdf2.GetBytes(32); $aes2.IV = [Convert]::FromBase64String($lines[2])
+    $check = [Convert]::FromBase64String($lines[3]); $check = $aes2.CreateDecryptor().TransformFinalBlock($check, 0, $check.Length)
+    if ([Convert]::ToBase64String($check) -ne [Convert]::ToBase64String($private)) { Write-Host "Verification FAILED - the backup is not usable"; exit 1 }
+    Write-Host "Backup written and verified: $ExportSigningKey (AES-256, PBKDF2-SHA256 300000) - keep it and the password safe"
+    exit 0
+}
+# Sicherung zurückspielen (neuer PC / Windows neu): Datei + Passwort -> wieder DPAPI-verschlüsselt in %USERPROFILE%\.msco
+if ($ImportSigningKey) {
+    if (-not (Test-Path -LiteralPath $ImportSigningKey)) { Write-Host "Not found: $ImportSigningKey (network drive? see -ExportSigningKey)"; exit 1 }
+    $lines = [IO.File]::ReadAllText($ImportSigningKey).Split("`n")
+    if ($lines.Count -lt 4 -or $lines[0].Trim() -ne "MSCO-SIGNING-KEY-BACKUP v1") { Write-Host "This is not an MSCO signing key backup"; exit 1 }
+    $plainPw = Get-BackupPassword "Password of the backup"
+    try {
+        $kdf = New-Object Security.Cryptography.Rfc2898DeriveBytes($plainPw, [Convert]::FromBase64String($lines[1]), 300000, [Security.Cryptography.HashAlgorithmName]::SHA256)
+        $aes = [Security.Cryptography.Aes]::Create(); $aes.Key = $kdf.GetBytes(32); $aes.IV = [Convert]::FromBase64String($lines[2])
+        $enc = [Convert]::FromBase64String($lines[3])
+        $private = $aes.CreateDecryptor().TransformFinalBlock($enc, 0, $enc.Length)
+        $rsa = New-Object System.Security.Cryptography.RSACng
+        $rsa.FromXmlString([Text.Encoding]::UTF8.GetString($private))
+    } catch { Write-Host "Wrong password or damaged backup"; exit 1 }
+    $target = Join-Path $secretDir "release-signing-key.dpapi"
+    if (Test-Path -LiteralPath $target) {
+        $current = [Security.Cryptography.ProtectedData]::Unprotect([IO.File]::ReadAllBytes($target), $keyEntropy, $scope)
+        if ([Convert]::ToBase64String($current) -eq [Convert]::ToBase64String($private)) { Write-Host "This key is already installed"; exit 0 }
+        Write-Host "There already is a different signing key in $target - not replaced"; exit 1
+    }
+    New-Item -ItemType Directory -Force -Path $secretDir | Out-Null
+    [IO.File]::WriteAllBytes($target, [Security.Cryptography.ProtectedData]::Protect($private, $keyEntropy, $scope))
+    Write-Host "Signing key restored to $target"
     exit 0
 }
 
-if (-not $Product -or -not $File) { Write-Host "Usage: release.ps1 -Product mod|launcher|installer -File <file>  |  -SaveToken  |  -NewSigningKey  |  -ExportSigningKey <file>"; exit 1 }
+if (-not $Product -or -not $File) { Write-Host "Usage: release.ps1 -Product mod|launcher|installer -File <file>  |  -SaveToken  |  -NewSigningKey  |  -ExportSigningKey <file>  |  -ImportSigningKey <file>"; exit 1 }
 
 if ($env:MSCO_NO_RELEASE -eq "1") { Write-Host "MSCO release: MSCO_NO_RELEASE=1 - not uploading."; exit 0 }
 $token = $env:MSCO_RELEASE_TOKEN