driver-signing

What this skill does

# Driver Signing & Certification - Quick Reference

> **Deep Knowledge**: Use `mcp__documentation__fetch_docs` with technology: `driver-signing`. Authoritative sources:
> - `learn.microsoft.com/en-us/windows-hardware/drivers/install/driver-signing`
> - `learn.microsoft.com/en-us/windows-hardware/drivers/dashboard/`

## The two signing tracks (post-Windows 10 1607)

| Track | What it gives you | Cost / time |
|-------|-------------------|-------------|
| **Attestation signing** (Partner Center) | A driver that loads on every modern Windows. No HLK tests, no logo. | EV cert (~$300-500/yr) + free attestation submission, hours-to-1-day turnaround |
| **WHQL / HLK certification** | "Certified for Windows" branding, can ship via Windows Update, broader test pass evidence | EV cert + HLK lab (your own or a partner) + submission, days-to-weeks |

**Both require an EV (Extended Validation) code-signing certificate** issued to your company. Standard OV/Authenticode certs are no longer accepted for kernel drivers as of 1607.

## What "kernel-mode signing" actually checks at load time

When `ntoskrnl` (or a UMDF reflector) loads a driver:
1. The `.sys` (or `.dll` for UMDF) must be Authenticode-signed
2. The signature chain must terminate at a Microsoft-issued cert (delivered via Partner Center attestation or WHQL flow)
3. Optionally page-hashes inside the PE are checked under HVCI

If the OS is in **test mode** (`bcdedit /set testsigning on`), the load policy is relaxed: any test-signed driver loads. **Test mode is for development only** — production users should never need it.

## Workflow: development → ship

```
[develop]   build .sys + .inf
   |
[test sign] makecert / signtool with self-signed test cert
   |        bcdedit /set testsigning on  (one-time on test box)
   |        load with pnputil /add-driver MyDrv.inf /install
   |
[verify]    SDV + CodeQL + Driver Verifier + (HLK if going WHQL)
   |
[package]   build a .cab containing INF + SYS + CAT (catalog) + co-files
   |        sign the .cab with EV cert (timestamped)
   |
[submit]    Partner Center → Hardware → Driver → New submission
   |        - attestation only (single OS family) or
   |        - HLK package + test results (full WHQL)
   |
[receive]   Microsoft signs the catalog — download signed package
   |
[ship]      Distribute the signed package via installer / Windows Update
```

## Test signing (development only)

```cmd
:: Create a self-signed test cert
makecert -r -pe -ss PrivateCertStore -n "CN=WDKTestCert" -eku 1.3.6.1.5.5.7.3.3 wdktest.cer

:: Sign the .sys
signtool sign /v /s PrivateCertStore /n WDKTestCert /t http://timestamp.digicert.com ^
    /fd sha256 MyDriver.sys

:: Generate the catalog from the INF
inf2cat /driver:C:\path\to\driverpkg /os:10_X64

:: Sign the catalog
signtool sign /v /s PrivateCertStore /n WDKTestCert /t http://timestamp.digicert.com ^
    /fd sha256 MyDriver.cat

:: Enable test signing on target machine (admin, requires reboot)
bcdedit /set testsigning on
```

## Production: attestation signing

Prerequisites:
1. **EV code-signing certificate** in a hardware token (DigiCert, Sectigo, GlobalSign — any provider in the Microsoft trust list)
2. **Partner Center account** with the Hardware program enabled (one-time EV-signed registration)
3. Driver passes `Inf2Cat` and `signtool verify /v /kp /a` clean

Build a **driver package** (`.cab`):
```cmd
:: 1. Layout in a folder:
::    pkg\
::      MyDriver.inf
::      MyDriver.sys
::      MyDriver.cat   <-- generated by inf2cat
::      <co-installers, additional bins>

:: 2. Make a CAB
makecab /D CabinetNameTemplate=MyDriverPackage.cab /D DiskDirectoryTemplate=. /F sources.ddf

:: 3. Sign the CAB with the EV cert
signtool sign /v /a /n "Your Company" /tr http://timestamp.digicert.com /td sha256 ^
    /fd sha256 MyDriverPackage.cab

:: 4. Upload via Partner Center → Hardware → Driver → New submission
::    Choose Submission type = Automatic / Attested / etc.
```

Microsoft signs the catalog inside the package and returns a signed package — that's what you ship.

## INF — what reviewers (and `infverif`) flag

Run `infverif.exe /v /w MyDriver.inf` for Windows 10/11 universal compliance:
- `Class` and `ClassGuid` must be one of the standard classes (or your custom class is **also** registered correctly)
- `CatalogFile=` directive must reference the `.cat`
- `DriverVer=` date format `MM/DD/YYYY,X.Y.Z.W` (date must be ≤ today, version monotonic)
- Architecture decorations: `[Standard.NT$ARCH$.10.0...19041]` (no NT5/XP-only sections)
- No deprecated `Include`/`Needs` patterns
- No co-installers unless absolutely needed (deprecated for universal drivers)
- File destination dirs must be in the allowed set (`12` = `\Drivers`, `13` = `\DriverStore`)

## WHQL / HLK in one paragraph

The Hardware Lab Kit is a Microsoft test harness: install the controller on one machine, the studio on another, point at your driver and device, choose a feature playlist (HID, Display, Mobile Broadband, etc.), and run. The output is a `.hlkx` package with logs + filters; you upload that with the signing submission. HLK takes hours to days depending on the playlist size; some scenarios need specific reference hardware.

## Dual signing (legacy + modern)

For drivers targeting Win7/8/8.1 in addition to Win10+, dual-sign with an SHA-1 cross-cert + an SHA-256 EV cert. Win7/8 won't trust SHA-256 only; Win10 1607+ won't trust unattested cross-signed drivers. Most new projects target 10+ only and skip the SHA-1 leg.

## Verifying a signed binary

```cmd
signtool verify /v /pa MyDriver.sys
signtool verify /v /kp /a MyDriver.sys     :: kernel policy
```

`/kp` simulates the kernel-mode policy check — if this fails, the driver won't load on production machines even with a valid signature.

## Anti-Patterns

| Anti-Pattern | Why It's Bad | Correct Approach |
|--------------|--------------|------------------|
| Shipping with `bcdedit testsigning on` instructions for end users | Disables a security boundary, support nightmare | Get EV + attestation signing |
| Standard OV cert (not EV) | Won't be accepted by Partner Center for drivers | Use a real EV cert in a hardware token |
| Forgetting the timestamp server | Signature expires when the cert expires | Always pass `/tr <RFC3161>` and `/td sha256` |
| Modifying the driver after `inf2cat` | Catalog hashes don't match → "WHQL fails", driver won't load | Re-run `inf2cat` and re-sign after every change |
| Co-installers in a universal driver package | Deprecated, breaks `infverif /v /w` | Move logic into `EvtDevicePrepareHardware` or a separate service |
| Mixing test-signed and production binaries in one INF | Catalog can't cover both | One INF per signing track |
| Shipping unsigned UMDF drivers because "they're user-mode" | Reflector still requires the catalog signed | Sign UMDF DLLs and INF the same way as KMDF |
| Forgetting `/kp` in verification | Loads on dev, fails on prod | Always run `signtool verify /v /kp /a` before shipping |