Cross-Certificates for Kernel Mode Code Signing

This information describes how to obtain and use cross-certificates for code-signing kernel-mode binary files for Microsoft Windows.

Note  Please also review Microsoft Security Advisory (2880823) "Deprecation of SHA-1 Hashing Algorithm for Microsoft Root Certificate Program" which describes a policy change wherein Microsoft will no longer allow root certificate authorities to issue X.509 certificates using the SHA-1 hashing algorithm for the purposes of SSL and code signing after January 1, 2016.

Cross-Certificates Overview

A cross-certificate is a digital certificate issued by one Certificate Authority (CA) that is used to sign the public key for the root certificate of another Certificate Authority. Cross-certificates provide a means to create a chain of trust from a single, trusted, root CA to multiple other CAs.

In Windows, cross-certificates:

  • Allow the operating system kernel to have a single trusted Microsoft root authority.
  • Extend the chain of trust to multiple commercial CAs that issue Software Publisher Certificates (SPCs), which are used for code-signing software for distribution, installation, and loading on Windows

The cross-certificates that are provided here are used with the Windows Driver Kit (WDK) code-signing tools for properly signing kernel-mode software. Digitally signing kernel-mode software is similar to code-signing any software that is published for Windows. Cross-certificates are added to the digital signature by the developer or software publisher when signing the kernel-mode software. The cross-certificate itself is added by the code-signing tools to the digital signature of the binary file or catalog.

See Authenticode Signing of Third-party CSPs for more information about how to use cross-certificates to sign third-party Cryptographic Service Providers (CSPs).

Selecting the Correct Cross-certificate

Microsoft provides a specific cross-certificate for each CA that issues SPCs for code-signing kernel-mode code. The list below has a link to the correct cross-certificate for the root authority that issued your SPC.

Follow the steps below to identify your CA, and then download the related cross-certificate.

  1. Open the Microsoft Management Console (MMC) and add the Certificates snap-in:

    1. Click the Start button, type “mmc” in the search box, and press return. If a User Account Control dialog box appears, click Yes.
    2. From the MMC File menu, select Add/Remove Snap-in, …
    3. Select the Certificates snap-in and click Add.
    4. Select My user account and click Finish.
    5. Select the Certificates snap-in again and click Add.
    6. Select Computer account and click Next.
    7. Select Local computer and click Finish.
  2. Locate your SPC in the certificate store, and then double-click it. Your certificate is listed in one of the following two locations, depending on how the certificate was installed.

    • The Current User, Personal, Certificates store, or
    • The Local Computer, Personal, Certificates store
  3. In the Certificate dialog box, click on the Certification Path tab, and then select the top-most certificate in the certification path. This is the CA that is the issuing root authority for your SPC.

  4. View the root authority certificate by clicking the View Certificate button, and then click the Details tab of the new Certificate dialog box.

  5. Find the Issuer and Thumbprint for this certificate. Then locate the corresponding entry for this CA in the list below.

  6. Download the related cross-certificate for the CA and use this cross-certificate together with your SPC when digitally signing kernel-mode code

Cross-Certificate List

The following list contains all of the CAs that are currently supported by Microsoft for issuing SPCs for code-signing kernel-mode code.

CA Root certificate thumbprint Download link
Certum Trusted Network CA 55 43 55 15 fd d2 48 65 75 fd c5 cf 3b ad 00 c9 13 12 3d 03 Download
DigiCert Assured ID Root CA ba 3e a5 4d 72 c1 45 d3 7c 25 5e 1e a4 0a fb c6 33 48 b9 6e Download
DigiCert Global Root CA c9 83 39 19 f1 f3 6a 63 48 11 1e 93 02 6f d4 0e b9 6f bc 34 Download
DigiCert High Assurance EV Root CA 2f 25 13 af 39 92 db 0a 3f 79 70 9f f8 14 3b 3f 7b d2 d1 43 Download Certification Authority (2048) 00 a3 e6 00 9e aa 73 9b 3d ee f4 b5 06 64 9d 8a 1a 7a d3 3a Download
Entrust Root Certification Authority – G2 ‎d8 fc 24 87 48 58 5e 17 3e fb fb 30 75 c4 b4 d6 0f 9d 8d 08 Download
GeoTrust Primary Certification Authority e8 6e 80 82 99 0e 3d fa ed 81 6d 9e b1 72 0f 91 a4 f1 a1 85 Download
GeoTrust Primary Certification Authority – G3 b2 bb bd fa c8 f1 a8 ad 58 95 cd 49 38 4b 22 ca 19 db 2d 1f Download
GlobalSign Root CA cc 1d ee bf 6d 55 c2 c9 06 1b a1 6f 10 a0 bf a6 97 9a 4a 32 Download
Go Daddy Root Certificate Authority – G2 84 2c 5c b3 4b 73 bb c5 ed 85 64 bd ed a7 86 96 7d 7b 42 ef Download
NetLock Arany (Class Gold) 89 4f 1d 28 97 aa 4c 07 4d cd 85 c5 fc 09 ee 73 b9 51 04 d8 Download
NetLock Platina (Class Platinum) 97 dd 74 97 16 20 57 29 41 dc 80 0c 2f d8 0a 48 07 7d 10 b0 Download
Security Communication RootCA1 41 f2 8c e5 6f d8 b9 cb 46 7f b5 03 2a 3c ae 1c dc 9d 86 48 Download
Starfield Root Certificate Authority – G2 40 c2 0a 9a 33 fa d0 36 ac bf e8 2d 6c bb ee 1b 42 9b 86 de Download
StartCom Certification Authority e6 06 9e 04 8d ea 8d 81 7a fc 41 88 b1 be f1 d8 88 d0 af 17 Download
TC TrustCenter Class 2 CA II 42 62 ff 7d 89 70 66 aa e7 75 80 d3 3a d2 88 03 f9 a1 1a 62 Download
Thawte Primary Root CA 55 38 e9 fe c1 40 30 b7 40 15 23 49 e1 15 a1 16 5d 29 07 4a Download
Thawte Primary Root CA – G3 ba 57 ca 5e 78 dd 2d 1d 74 76 ae be e9 95 3e 39 6f d0 55 46 Download
VeriSign Class 3 Public Primary Certification Authority – G5 57 53 4c cc 33 91 4c 41 f7 0e 2c bb 21 03 a1 db 18 81 7d 8b Download
VeriSign Universal Root Certification Authority 9e d8 cd 56 01 f0 10 56 51 eb bb 3f 57 f0 31 82 e5 fa 7e 01 Download

New Cross-Certificate List

The following list contains several new CAs that are currently supported by Microsoft for issuing SPCs for code-signing kernel-mode code.

CA Root certificate thumbprint Download link
AddTrust External CA Root a7 5a c6 57 aa 7a 4c df e5 f9 de 39 3e 69 ef ca b6 59 d2 50 Download
GoDaddy Class 2 Certification Authority d9 61 24 72 ef 0f 27 87 e2 b2 d9 e0 63 a0 6b 32 fa 5e 33 3d Download
Starfield Class 2 Certification Authority f8 fc 7f 3c dd 51 76 ad d2 7c f9 7f 73 96 59 09 46 6d 9a 22 Download
UTN-USERFirst-Object ae 1e 25 26 01 30 a3 0b 1b c2 20 29 35 65 3b e5 a7 23 be f5 Download