Always On VPN ECDSA SSL Certificate Request for SSTP

As I’ve discussed previously, it is strongly recommended that the TLS certificate used for SSTP be signed using the Elliptic Curve Digital Signature Algorithm (ECDSA). ECDSA provides better security and performance compared to RSA certificates for Windows 10 Always On VPN connections using SSTP. See my previous post Always On VPN SSL Certificate Requirements for SSTP for more information.

Certificate Signing Request

To generate a Certificate Signing Request (CSR) using ECDSA to send to a public Certification Authority (CA), open the local computer certificate store (certlm.msc) on any Windows server or client and follow the steps below.

  1. Expand Certificates – Local Computer.
  2. Right-click the Personal folder and choose All Tasks > Advanced Operations > Create Custom Request.
  3. Click Next.
  4. Select Proceed without enrollment policy.
  5. Click Next.
  6. From the Template drop-down list choose (No template) CNG key.
  7. Click Next.
  8. Click Details.Always On VPN ECDSA SSL Certificate Request for SSTP
  9. Click Properties.
  10. On the General tab enter a name in the Friendly name field.
  11. Click on the Subject tab.
    1. In the Subject name section, from the Type drop-down list choose Common name.
    2. In the Value field enter the VPN server’s public hostname and click Add.
    3. In the Alternative name section, from the Type drop-down list choose DNS.
    4. In the Value field enter the VPN server’s public hostname and click Add.Always On VPN ECDSA SSL Certificate Request for SSTP
  12. Click on the Extensions tab.
    1. Expand Extended Key Usage (application policies).
    2. Highlight Server Authentication.
    3. Click Add.Always On VPN ECDSA SSL Certificate Request for SSTP
  13. Click on the Private Key tab.
    1. Expand Cryptographic Service Provider.
    2. Uncheck RSA,Microsoft Software Key Storage Provider.
    3. Check ECDSA_P256,Microsoft Software Key Storage Provider.Always On VPN ECDSA SSL Certificate Request for SSTP
  14. Expand Key options.
    1. Select the option to Make private key exportable.Always On VPN ECDSA SSL Certificate Request for SSTP
  15. Click Ok.
  16. Click Next.
  17. Enter a name for the file in the File Name field.
  18. Click Finish.

Submit the Request

Once complete, submit the CSR for signing to your favorite public CA. Based on my experience, some CAs are easier to obtain ECDSA-signed certificates than other. Today, Digicert seems to be one of the better public CAs for obtaining EC TLS certificates.

Complete the Request

Once the CA has issued the certificate, import the certificate in to the local computer certificate store on the same client or server where the original CSR was created. The certificate can then be exported and imported on additional VPN servers, if required.

Additional Information

Always On VPN SSL Certificate Requirements for SSTP

Always On VPN Protocol Recommendations for RRAS

 

Leave a comment

7 Comments

  1. Tony

     /  August 20, 2018

    Hi Richard, can this be used for the IKEv2 Certificate as well? As I want to combine SSL and IKEv2 Certificate as one public certificate.

    Thanks
    Tony

    Reply
    • The IKEv2 certificate should not be issued by a public CA. It should be issued by an internal CA as it is used to map your users to their accounts in Active Directory.

      Reply
  2. Chris

     /  January 4, 2019

    Hi Richard

    In the certificate signing request properties on the extensions tab, in the ‘Extended Key Usage’ section do we need to select server authentication?

    Also on the Private key tab under ‘Key Options’ do we need to tick ‘Make private key exportable’ as we have a number of VPN servers that need the public cert

    Thanks

    Chris

    Reply
    • You can certainly do those things, yes. However, in my experience most Certification Authorities will include both Server Authentication and Client Authenticate regardless. They’ll usually mark them as exportable too. However, I will update the post to include those settings for completeness. 🙂

      Reply
  1. Always On VPN SSL Certificate Requirements for SSTP | Richard M. Hicks Consulting, Inc.
  2. Troubleshooting Always On VPN Error Code 0x80092013 | Richard M. Hicks Consulting, Inc.

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