question

Hi Mike-6205,

Here’s the Step-by-Step to creating a self certified certificate to support 256 bit:

Run PowerShell as administrator

Run the following command to create the certificate:

New-SelfSignedCertificate –DnsName <Computer name> -CertStoreLocation “cert:\LocalMachine\My”

Next, we need to add the self-signed certificate as a trusted certificate authority...
Run MMC -32 as administrator

Select File > Add or Remove Snap-ins

Select Certificates and then click Add

Select Computer account and press Next

Select Local computer, then click Finish. Then Click OK.

Find the certificate in Personal > Certificates:

Right-click on the newly created certificate and then select Properties. Input the desired Friendly Name field for the certificate based upon what you are testing. Once completed, select the Apply button followed by OK.

Right-click on the certificate and choose Copy

Expand Trusted Root Certificate Authorities

Right-click on the Certificates folder

Select Paste

In IIS Manager (usually requiring Administrator permissions), you can now see the self-signed certificate with SHA-256 as the SSL certificate.

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Hi,

The certificate doesn't control which cipher will be used for the connection encryption, the server and client negotiate a mutually agreed cipher. If you want to control which cipher is used, you will need to limit what cipher are supported by the server.

Have a look at this article on Ciphers https://en.wikipedia.org/wiki/Cipher_suite

This one to control the ciphers which ciphers are enabled https://dirteam.com/sander/2019/07/30/howto-disable-weak-protocols-cipher-suites-and-hashing-algorithms-on-web-application-proxies-ad-fs-servers-and-windows-servers-running-azure-ad-connect/

Gary.